Strangeness in Quark Matter 2024 (SQM 2024)

Room Curie (Université de Strasbourg / Palais de la Musique et des Congrès)

Room Curie

Université de Strasbourg / Palais de la Musique et des Congrès

Strasbourg, France

The 21st International Conference on Strangeness in Quark Matter (SQM 2024) will focus on new experimental and theoretical developments on the role of strange and heavy-flavour quarks in high energy heavy-ion collisions and in astrophysical phenomena.

Scientific topics include:

  • Strangeness and heavy-quark production in nuclear collisions and hadronic interactions
  • Hadron resonances in the sQGP (strongly-interacting Quark-Gluon Plasma)
  • Bulk matter phenomena associated with strange and other heavy quarks
  • Chirality, vorticity and spin polarisation phenomena
  • Strangeness in astrophysics
  • QCD phase structure
  • Collectivity in small systems
  • Open questions and new developments
    • Registration: Student registration Amphithéâtre Augustin Jean Fresnel (Faculté de Physique et d'Ingénierie)

      Amphithéâtre Augustin Jean Fresnel

      Faculté de Physique et d'Ingénierie

      3 Rue de l'Université
    • Student Lecture

      Lectures dedicated to students on Sunday 02/06

      • 1
        Lecture 1
        Speaker: David Chinellato (Austrian Academy of Sciences, Stefan Meyer Institute For Subatomic Physics)
      • 10:40 AM
        Coffee break
      • 2
        Lecture 2
        Speaker: Auguste Besson (Institut Pluridisciplinaire Hubert Curien)
    • 12:30 PM
      Lunch break Room Curie

      Room Curie

      Université de Strasbourg / Palais de la Musique et des Congrès

      Strasbourg, France
    • Student Lecture

      Lectures dedicated to students on Sunday 02/06

      • 3
        Lecture 3
        Speaker: Jean-Yves Ollitrault (IPhT Saclay)
      • 3:50 PM
        Coffee Break
      • 4
        Lecture 4
        Speaker: Pol Gossiaux (Subatech)
    • Registration: Registration 03-06 Palais de la Musique et des Congrès de Strasbourg

      Palais de la Musique et des Congrès de Strasbourg

      Convener: Fanny Viala-Vanardois
    • Opening: Institutional introductions Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Berndt Mueller (Duke University)
    • Plenary-Overviews: Th+Exp Overviews Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Berndt Mueller (Duke University)
      • 5
        Theory Overview / State-of-the-art
        Speaker: Jacquelyn Noronha-Hostler (University of Illinois Urbana-Champaign)
      • 6
        Experiment Overview / State-of-the-art
        Speaker: Maximiliano Puccio (CERN)
    • 10:15 AM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Plenaries-Highlights Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Johanna Stachel (University of Heidelberg)
      • 7
        Recent results on light flavours and correlations from ALICE
        Speaker: Mesut Arslandok (Yale)
      • 8
        Recent results on heavy flavours and quarkonia from ALICE
        Speakers: Fiorella Fionda (University & INFN, Cagliari), Fiorella Maria Celeste Fionda (University & INFN, Cagliari)
      • 9
        CMS highlights: Recent results from CMS
        Speakers: Florian Damas (Laboratoire Leprince-Ringuet (CNRS/IN2P3, France)), Florian Damas (LLR)
      • 10
        LHCb highlights: Recent results from LHCb
        Speaker: Thomas Boettcher (University of Cincinnati)
      • 11
        ATLAS highlights: Recent results from ATLAS

        ATLAS highlights: Recent results from ATLAS

        This talk presents an overview of recent ATLAS measurements in heavy ion collision systems.
        These include multiple measurements of jet production and jet structure, which probe the dynamics of the hot, dense Quark-Gluon Plasma formed in relativistic nucleus-nucleus collisions, and measurements of quarkonia and heavy flavor production to probe the QGP medium properties.
        Furthermore, an overview of the latest ultra-peripheral physics measurements performed, including both measurements of photo-nuclear and photon-photon fusion processes, will be discussed.
        The photo-nuclear events can provide a clean probe of the partonic structure of the nucleus analogous to deep inelastic scattering while studies of processes in photon-photon interactions constraints the nuclear photon flux, the tau lepton's anomalous magnetic dipole moment (g-2), and provide a unique opportunity to investigate extensions of the Standard Model.

        Speaker: Petr Balek (AGH University of Krakow)
    • 12:30 PM
      Lunch break Room Étoile

      Room Étoile

    • Plenaries-Highlights Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Jürgen Schukraft (CERN)
      • 12
        STAR highlights: Recent results from STAR

        Qian Yang, for the STAR Collaboration

        STAR is a multipurpose detector with excellent particle identification capabilities, operating at Relativistic Heavy Ion Collider (RHIC) at BNL.
        Recently, STAR has completed data taking for the second phase of the Beam Energy Scan program at RHIC (BES-II) and the Isobar collisions program. The BES-II program includes dedicated low beam energy runs and a fixed-target program covering the energy range $\sqrt{s_{NN}}$ = 3 -19.6 GeV/$c^{2}$, allowing for exploration of the high baryon density region of the QCD physics.
        The BES-II program also includes iTPC, EPD and eTOF detector upgrades which will increase STAR's acceptance both in rapidity and low transverse momentum and extent its particle identification capabilities.
        With new datasets and dataset from U+U and d+Au collisions, STAR collaboration will present a series of measurements related to charged particles, strange hadrons, heavy quarks, dielectrons, light nuclei as well as hypernuclei. STAR is also taking high statistics p+p and Au+Au data in RHIC runs from 2023-25 with dedicated forward upgrades and the detector upgrades from BES-II. These datasets provide unique opportunities to investigate the microstructure of Quark-Gluon Plasma (QGP) and the unique forward cold QCD physics.
        The outlook on these measurements will also be discussed.

        Speaker: Qian Yang
      • 13
        PHENIX highlights: Recent results from PHENIX
        Speaker: Maya Shimomura
      • 14
        sPHENIX highlights: Recent results from sPHENIX

        sPHENIX is a new state-of-the-art detector constructed at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC). It was commissioned and took first Au+Au collision's data in the RHIC Run-2023.
        It seeks to answer fundamental questions on the nature of the quark-gluon plasma (QGP), including its coupling strength and temperature dependence, by using a suite of precision jet and $\Upsilon$ measurements that probe different length scales of the QGP. This is possible with its full acceptance, $\mid \eta \mid < $ 1 and 0$-$2$\pi$ in $\phi$, electromagnetic and hadronic calorimeters and precision tracking enabled by a 1.5 T superconducting magnet. With the increased luminosity afforded by accelerator upgrades, sPHENIX will perform high statistics measurements extending the kinematic reach at RHIC to overlap the LHC’s. This overlap will facilitate a better understanding of the role of temperature, density and parton virtuality in QGP dynamics and, specifically, jet quenching.
        This talk will discuss the present detector status in the ongoing RHIC Run-2024, as well as highlights on first physics measurements in Au+Au collisions at $\sqrt{s_{_{NN} }}$ = 200 GeV obtained from RHIC Run-2023.

        Speaker: Rachid Nouicer (Brookhaven National Laboratory)
    • Plenary-Overviews: Plenary-Overview: Theory Overviews Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Jürgen Schukraft (CERN)
      • 15
        Transport models – State of the art
        Speaker: Steffen Bass (Duke University)
    • 3:45 PM
      Coffee break Hall Berckheim

      Hall Berckheim

      Salle Berckheim

    • Plenaries-Highlights Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Claudia Ratti (University of Houston)
      • 16
        NA61/SHINE highlights: Recent results from NA61/SHINE

        News from NA61/SHINE

        The NA61/SHINE experiment at the CERN SPS is a multipurpose fixed-target spectrometer for charged and neutral hadron measurements. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. A significant advantage of NA61/SHINE over collider experiments is its extended coverage of phase space available for hadron production. The latter includes the nearly entire forward hemisphere for charged hadrons and additionally, also a large part of the backward hemisphere for specific neutrals.

        This talk will summarize the substantial package of new strangeness-related results, obtained by NA61/SHINE since the last Strangeness in Quark Matter conference (Busan, 2022). The latter will include preliminary and final data on strange baryon and strange meson production ($\Lambda$, $K$, $K^*$, and others) in proton-proton, pion-nucleus and nucleus-nucleus collisions in the collision energy range $\sqrt{s_{NN}}=$5-17 GeV. Particular attention will be devoted to the difference observed between charged and neutral $K$ mesons production in Ar+Sc reactions, up to now not understood by existing models.

        Speaker: Andrzej Rybicki
      • 17
        HADES highlights: Recent results from HADES
        Speaker: Manuel Lorenz
    • Plenary-Overviews: Theory Overviews (PlenOverview) Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Claudia Ratti (University of Houston)
      • 18
        Strangeness in astrophysics

        Over the past decades strangeness has received a lot attention in connection with the study of exotic atoms, the analysis of the production and propagation of strange hadrons in particle research facilities as well as the investigation of the possible strange phases in the interior of compact stars, such as neutron stars. In this talk I will address strange dense matter inside neutron stars, paying a special attention to the consequences for the structure of these compact stellar objects and the dynamics of neutron star mergers.

        Speakers: LAURA TOLOS RIGUEIRO (ICE (CSIC, Barcelona)), Dr Laura Tolos (University of Frankfurt & ICE (Barcelona))
      • 19
        Recent progress on the QCD phase diagram and the equation of state
        Speaker: Gergely Endrödi (Bielefeld University)
    • 6:30 PM
      Reception at PMC - Wine & Cheese Hall Schweitzer

      Hall Schweitzer

    • Track1-LF Room Madrid (Palais de la Musique et des Congrès)

      Room Madrid

      Palais de la Musique et des Congrès

      Convener: Huan Huang (UCLA Physics and Astronomy)
      • 20
        (TbC) Disoriented Isospin Condensates as source of anomalous kaon correlations at LHC

        Heavy-ion collision experiments produce the deconfined state of nuclear matter, the quark-gluon plasma (QGP). At QGP temperatures, the vacuum condensate is expected to melt leading to the restoration of the approximate chiral symmetry of QCD. As the plasma expands and cools, the chiral condensates are formed again. So far, concrete experimental evidence of this widely expected phenomena has proved elusive. The ALICE collaboration has reported anomalous correlations between charged and neutral kaons in Pb-Pb collisions at the LHC. We show that the measurements cannot be explained by usual statistical models but can be explained by invoking domains of flat neutral kaon fraction distribution. Such domains can be related to the fluctuations of the up and down quark condensates as the vacuum refreezes.

        Speaker: Mayank Singh (Vanderbilt University)
      • 21
        Large isospin symmetry breaking in kaon production at high energies

        It is well known that isospin symmetry is fulfilled to a good approximation in strong interactions, as confirmed in low-energy scattering experiments and in mass spectra of both light and heavy hadrons. In collisions of nuclei with an equal number of protons and neutrons, isospin symmetry imposes that the number of produced charged kaons should equal the number of neutral ones. The NA61/SHINE experiment at CERN recently reported an excess of charged over neutral kaon production in high-energy nucleus-nucleus collisions. Here, we argue that the measured charge-to-neutral kaon ratio of about 1.2 indicates an unexpectedly large violation of isospin symmetry. Using well-established models for hadron production, we demonstrate that known symmetry-breaking effects and the initial nuclei containing more neutrons than protons lead only to a small (few per cent) deviation from unity at high energies. Thus, they cannot explain the measurements. The significance of the isospin symmetry violation beyond the known effects is 5.5⋅σ when errors quoted by the experiments are used and 8.1 ⋅σ for the PDG-like scaled errors. New systematic, high-precision measurements and theoretical efforts are needed to establish the origin of the observed large isospin-symmetry breaking.

        Speaker: Francesco Giacosa (Jan kochanowski university)
      • 22
        Investigating the nature of the K$^*_0$(700) state with $\pi^{\pm}$ $K^0_S$ correlations with ALICE at the LHC

        The first measurements of femtoscopic correlations with the particle-pair combinations $\pi^{\pm}$ $K^0_S$ in pp collisions at $\sqrt{s}$ = 13 TeV are reported by ALICE. It is shown that it is possible to study the elusive $K^*_0(700)$ particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a $\pi^{\pm}$ $K^0_S$ pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter of the final-state interaction are found to be consistent with previous measurements of the $K^*_0(700)$. The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the $K^*_0(700)$ is a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the $K^*_0(700)$ resonance.

        Speaker: Thomas Humanic
      • 23
        Production of $\Sigma$ baryons as a function of multiplicity in pp collisions at the LHC with ALICE

        The strangeness content of the final state in ultrarelativistic heavy ion collisions has been studied through measurements of kaons, $\Lambda$, Ξ and $\Omega$ baryons in pp, pA and AA collisions. $\Sigma$ baryons contain a single strange quark and form a triplet, with the charge (+, 0, -) depending on the light quark content. In a thermal model scenario, these states are abundant enough to carry a significant fraction of the strangeness produced in the collision. However, the experimental measurement is challenging, and to date only $\Sigma^{0}$ in 7 TeV pp collisions have been measured by ALICE, while few other experiments have measured the charged states at lower pp($\rm p \bar{\rm p}$) collision energies.
        A number of methods to identify charged Σ have been developed by ALICE during the LHC Run 2. The decay $\Sigma^{+}$ $\rightarrow$ p $\pi^{0}$ can be reconstructed via the direct detection of the proton and the two gammas from the $\pi^{0}$ decay, either through double conversion into $\rm e^{+}e^{-}$ pairs or through one converting and the other being reconstructed in the Photon Spectrometer (PHOS). Additionally, a method to detect anti-neutrons in the PHOS has been developed, allowing the $(anti-\Sigma)^±$ $\rightarrow$ anti-n + $\pi^{\pm}$ decays to be reconstructed. We present the transverse momentum spectra of $\Sigma^{+}$ and its charge conjugate anti-particle, in both minimum bias and high-multiplicity triggered pp collisions at $\sqrt{s} = 13$ TeV. These are then compared to the latest MC simulations, including different PYTHIA tunings, which best reproduce the existing hyperon data.
        With the advent of Run 3, ALICE has improved the capability of the Inner Tracker, allowing the detection of the charged Σ particle with the reconstruction of its decay after traversing several detector layers. The performance of this novel reconstruction method is discussed. In addition, the prospects for measurements of the interaction between Σ and other baryon species will be discussed together with the implications for constraining the neutron star equation of state.

        Speaker: Pavel Gordeev
      • 24
        A Deep Learning Based Estimator for Light Flavour Elliptic Flow in Heavy Ion Collisions at RHIC and LHC Energies

        Recent developments on a deep learning feed-forward network for estimating elliptic flow ($v_2$) coefficients in heavy-ion collisions have shown us the prediction power of this technique. The success of the model is mainly the estimation of $v_2$ from final state particle kinematic information and learning the centrality and the transverse momentum ($p_T$) dependence of $v_2$. The deep learning model is trained with Pb-Pb collisions at 5.02 TeV minimum bias events simulated with a multiphase transport model (AMPT). We extend this work to estimate v2 for light-flavor identified particles such as $\pi ^{\pm}$, $K^{\pm}$, and $p+\bar{p}$ in heavy-ion collisions at RHIC and LHC energies. The number of constituent quark (NCQ) scaling is also shown. The evolution of pT-crossing point of $v_2(p_T)$, depicting a change in meson- baryon elliptic flow at intermediate-pT, is studied for various collision systems and energies. The model is further evaluated by training it for different $p_T$ regions. These results are compared with the available experimental data wherever possible for light hadrons.

        [1] Physical Review D 105, 114022 (2022)
        [2] Phys. Rev. D 107, 094001 (2023)

        Speaker: Gergely Barnafoldi (HUN-REN Wigner RCP)
    • Track2-HF&Q Room Rome (Palais de la Musique et des Congrès)

      Room Rome

      Palais de la Musique et des Congrès

      Convener: Joerg Aichelin (SUBATECH)
      • 25
        Heavy Flavour Energy Loss in Small and Large Systems

        We present novel predictions for high-$p_T$ heavy flavour $D$ and $B$ meson suppression in $p + p$, $p + A$, $d + A$ and $A + A$ collisions at RHIC and the LHC.  These predictions are made using a one-parameter convolved elastic and radiative energy loss model, which receives small system size corrections to both the elastic and radiative energy loss.  We simultaneously predict the observed light flavour pion $R_{AA}$  in both Au + Au and $d$ + Au collisions at RHIC, providing additional supporting evidence that QGP is formed in high-multiplicity $d$  + Au collisions at $\sqrt{s}=200$ AGeV.  Our results are also consistent with the suppression of both light and heavy flavours in Pb + Pb collisions at the LHC. We are unable to reproduce the observed lack of suppression in high-multiplicity $p$ + Pb collisions at the LHC.  We propose that a system size scan will help separate radiative and elastic dominated suppression, as well as various theoretical uncertainties in HTL-based elastic energy loss. Predictions, along with a detailed theoretical uncertainty analysis, are presented for such a future system size scan including $p+p$, $p+A$, $d + A$, $^{3}\mathrm{He} + A$ , $p+\mathrm{O}$, $\mathrm{O} + \mathrm{O}$, $\mathrm{Xe} + \mathrm{Xe}$, and $\mathrm{Pb} + \mathrm{Pb}$ collision systems.

        Speaker: Coleridge Faraday (University of Cape Town)
      • 26
        Mass hierarchy of heavy quark energy loss within a perturbative-non-perturbative transport model

        The general intuition that heavier partons suffer weaker energy loss inside a quark-gluon plasma (QGP) medium is critically re-examined. Within a linear Boltzmann transport model that includes both Yukawa and string types of interactions between heavy quarks and the QGP, we find that while the radiative energy loss is suppressed by the parton mass, heavier partons can experience stronger string potential scatterings with the medium. Their competition may result in less energy loss of bottom quarks than charm quarks at low transverse momentum ($p_\mathrm{T}$) but an inverse order at high $p_\mathrm{T}$. Our model calculation shows a weaker nuclear modification on bottom particles than charm particles at low $p_\mathrm{T}$, as observed by both RHIC and LHC experiments, but predicts an opposite hierarchy at high $p_\mathrm{T}$. A larger momentum space transport coefficient ($\hat{q}$) and a smaller spatial diffusion coefficient ($D_\mathrm{s}$) are found for bottom quarks than for charm quarks.

        Reference: arxiv 2307.14808

        Speaker: Yichao Dang (Shandong University)
      • 27
        Charm and Bottom hadron production with a coalescence plus fragmentation hadronization approach: AA system size scan down to pp collisions

        Heavy baryon production in pp, pA, and AA collisions from RHIC to top LHC energies presents a challenge for the theoretical understanding of heavy-quark hadronization. An hybrid approach of coalescence plus fragmentation has been successful in accurately predicting the large baryon-to-meson ratio $\Lambda_c/D^0\sim O(1)$ observed in both AA collisions at RHIC and LHC [1], as well as in pp collisions at $5.02$ and $13 \rm ;TeV$ [2]. Generally, the obtained ratio is significantly larger than those measured and expected in $e^+e^-$ and $ep$ collisions. Additionally, the same approach predicts a significant $\Xi_c/D^0\sim 0.15$ and $\Omega_c/D^0\sim 0.05$ enhancement in $pp$ collisions at $5.02 \rm ;TeV$, showing promising agreement with early ALICE measurements [2]. Furthermore, we discuss the extension of the hadronization approach to provide the first predictions for the multi-charmed baryon: $\Xi_{cc}$, $\Omega_{cc}$ and $\Omega_{ccc}$. Furthermore, we explore the evolution of the yield over a wide system size scan from $PbPb$ to $KrKr$, $ArAr$ and $OO$ as planned by ALICE3 [3].
        This study allow to investigate the impact on the production coming from non-equilibrium in the charm quark distribution. We find that, generally, the predicted yield in $PbPb$ collision are quite similar to SHM if full thermalization is assumed, but on the other hand multi-charmed baryon, especially $\Omega_{ccc}$, are particularly sensitive to the degree of thermalization of the charm quark distribution. Finally, we present the predictions of the hybrid hadronization via coalescence and fragmentation for bottom hadrons $B$ meson $\Lambda_b$ and $\Xi_b$baryons and their ratios for PbPb and pp collision at top LHC energies [4].
        The comparison between charm and bottom hadron production will provide a novel and more powerful insight not only into the hadronization mechanism but also into the charm and bottom quark equilibration dynamics versus the system size of colliding nuclei.

        [1] S. Plumari, V. Minissale, S.K. Das, G. Coci and V. Greco, Eur.Phys.J. C 78 (2018) no.4, 348
        [2] V. Minissale, S. Plumari and V. Greco, Physics Letters B 821 (2021) 136622.
        [3] V. Minissale, S. Plumari, Y. Sun and V. Greco, arXiv:2305.03687.
        [4] V. Minissale, S. Plumari and V. Greco, in preparation.

        Speaker: Prof. Salvatore Plumari (Università studi di Catania, INFN-LNS)
      • 28
        Investigation of charm-quark hadronisation into baryons in hadronic collisions with ALICE

        Charm-baryon production measurements in proton-proton (pp) collisions at the LHC are fundamental to investigate the charm-quark hadronisation, and to test perturbative QCD-based calculations. Measurements in pp collisions showed baryon-to-meson ratios significantly higher than those in $\mathrm{e^+e^-}$ collisions, suggesting that the hadronisation of charm quarks is not universal across collision systems. They challenge the validity of theoretical calculations based on the factorisation approach, which assume universal fragmentation functions across collision systems. Similar measurements in hadronic collisions as a function of the event multiplicity provide sensitive tools to explore how the formation of charm baryons is influenced by different processes from small to large colliding systems. Lastly, measurements of charm baryon-to-meson yield ratios in p–nucleus and nucleus–nucleus collisions provide crucial information about possible modifications of hadronisation mechanisms in presence of, respectively, cold nuclear-matter effects and final-state effects induced by the formation of a quark–gluon plasma (QGP).

        In this contribution, the final results of the ALICE Collaboration obtained by measuring the production of strange ($\Xi_\mathrm{c}^{0,+}$, $\Omega_\mathrm{c}^0$) and non-strange ($\Lambda_\mathrm{c}^+$, $\Sigma_\mathrm{c}^{0,+,++}$) charm baryons in pp, p–Pb collisions and that of $\Lambda_\mathrm{c}^+$ baryons in Pb–Pb collisions collected during the LHC Run 2 with the ALICE experiment are shown. A comparison between baryon-to-meson ratios with novel theoretical models implementing hadronisation mechanisms different from the fragmentation in the vacuum will be also discussed. The first studies of charm-baryon reconstruction using the large data sample of pp collisions at √s = 13.6 TeV harvested from the start of LHC Run 3 are presented.

        Speaker: JaeYoon Cho (Inha University)
      • 29
        Investigating Bottom Quark Energy Loss, Hadronization, and $\mathrm{B}$ Meson Nuclear Modification Factors in $\mathrm{B}^{+}$ and $\mathrm{B}_{s}^{0}$ Decays: Insights from CMS in pp, pPb, and PbPb Collisions

        The exclusive decay channels $\mathrm{B}_{\mathrm{s}}^{0}\to \mathrm{J}/\psi \phi$ and $\mathrm{B}^{+}\to\mathrm{J}/\psi K^{+}$ are investigated. The differential cross sections of $\mathrm{B}_{\mathrm{s}}^{0}$ and $\mathrm{B}^+$ mesons as a function of their transverse momenta ($p_\mathrm{T}$) in proton-proton collisions at 5.02 TeV are well-described by fixed-order plus next-to-leading logarithm calculations, using an integrated luminosity of 302.3 pb$^{-1}$. By utilizing previous lead-lead collision data at the same nucleon-nucleon (NN) center of mass energy, $R_{\mathrm{AA}}$ factors for the B mesons are determined. Additionally, the measurement of the $\mathrm{B}^+$ meson production cross section is presented with respect to meson $p_\mathrm{T}$ inclusively and, for the first time, in different charged particle multiplicity ranges. This study is conducted in proton-lead collisions at NN center-of-mass energy of $8.16~\mathrm{TeV}$, utilizing data collected by the CMS detector in 2016 with an integrated luminosity of 175 nb$^{-1}$. The analysis focuses on the exclusive decay channel $\mathrm{B}^{+}\to \mathrm{J}/\psi K^{+}$. Inclusive results demonstrate good agreement with fixed-order next-to-leading log calculations, and the ratio of nuclear modification factors is measured for different charged particle multiplicities. These studies provide a comprehensive understanding of $\mathrm{B}_{\mathrm{s}}^{0}$ and $\mathrm{B}^+$ meson production, shedding light on their behavior in different collision environments and offering insights into the nuclear modification factors associated with these mesons.

        Speaker: Jhovanny Andres Mejia Guisao
    • Track4-Bulk&Phase: 5 talks Room Bruxelles (Palais de la Musique et des Congrès)

      Room Bruxelles

      Palais de la Musique et des Congrès

      Convener: Prof. Elena Bratkovskaya (GSI, Darmstadt & Frankfurt Uni.)
      • 30
        Bayesian constraints on the high density QCD EoS from Heavy-ion collision data

        The Equation of State (EoS) of QCD matter for baryon densities ranging from 2 to 6 times saturation densities ($n_0$) is explored using a Bayesian framework [1]. A novel method [2] is employed to introduce any density-dependent EoS in UrQMD, allowing inference on a parameterizable EoS within the molecular dynamics part of the transport model. Au- Au collision data from different heavy-ion collision experiments in the beam energy range of $\sqrt{s_{\mathrm{NN}}}=$2 - 10 GeV are used to construct the posterior distribution for the density dependence of the EoS. The techniques, challenges and solutions involved in the analyses will be outlined.

        It is found that the proton observables used in the study tightly constrain the EoS from 2- 4.5 $n_0$. However the constraints on the EoS beyond 3 $n_0$ are highly sensitive to the choice of observations. I will also show new results on how the UrQMD+CMF framework allows us to also study the effect of hyperon interaction, with hyperon flow measurements, which is important for the understanding of the role of strange matter in neutron stars. This highlights the need for accurate measurements by experiments in the collision range of $\sqrt{s_{\mathrm{NN}}}=$ 2 - 10 GeV which can be achieved through the RHIC BES run and in the HADES+CBM @FAIR Experiments.

        [1] Omana Kuttan, M., Steinheimer, J., Zhou, K., & Stoecker, H. (2023).
        QCD Equation of State of Dense Nuclear Matter from a Bayesian Analysis of Heavy-Ion Collision Data. Physical Review Letters, 131(20), 202303.

        [2] Omana Kuttan, M., Motornenko, A., Steinheimer, J., Stoecker, H., Nara, Y., & Bleicher, M. (2022). A chiral mean-field equation-of-state in UrQMD: effects on the heavy ion compression stage. The European Physical Journal C, 82(5), 1-12.

        Speaker: Dr Manjunath Omana Kuttan (Frankfurt Institute for Advanced Studies)
      • 31
        4D-TExS: A new 4D lattice-QCD equation of state with extended density coverage

        Although calculations of QCD thermodynamics from first-principle lattice simulations are limited to zero net-density due to the fermion sign problem, several methods have been developed to extend the equation of state (EoS) to finite values of the $B, Q, S$ chemical potentials. Taylor expansion around $\mu_i = 0$ ($i=B,Q,S$) enables to cover with confidence the region up to $\mu_i/T < 2.5$. Recently, a new method has been developed to compute a 2D EoS in the $(T, \mu_B)$ plane. It was constructed through a T-Expansion Scheme (TExS), based on a resummation of the Taylor expansion, and is trusted up to densities around $\mu_B/T = 3.5$. We present here the new 4D-TExS EoS, a generalization of the TExS to all 3 chemical potentials, offering a larger coverage than the 4D Taylor expansion EoS. After explaining the basics of the T-Expansion Scheme and how it is generalized to multiple dimensions, we will present results for thermodynamic observables as functions of temperature and all chemical potentials.

        Speaker: Dr Johannes Jahan (University of Houston)
      • 32
        Equilibrium expectations for non-Gaussian fluctuations near a QCD critical point

        With the highly anticipated results from the Beam Energy Scan II program at RHIC coming soon, an understanding of particle-number fluctuations and their significance as a potential signature of a possible QCD critical point is crucial. Early works that embarked on this endeavor sought to estimate the fluctuations due to the presence of a critical point assuming they stay in equilibrium [1,2]. From these results came the proposal to focus efforts on higher, non-Gaussian, moments of the event-by-event distributions, in particular of the number of protons. These non-Gaussian moments are especially sensitive to critical fluctuations, as their magnitudes are proportional to high powers of the critical correlation length. As the equation of state provides key input for hydrodynamical simulations of heavy-ion collisions, we estimate equilibrium fluctuations from the BEST equation of state (EoS) that includes critical features from the 3D Ising Model [3,4,5]. In particular, the net-baryon kurtosis and its dependence on non-universal mapping parameters is investigated within the BEST EoS [6]. Furthermore, the correlation length, as a central quantity for the assessment of fluctuations in the vicinity of a critical point, is also calculated in a consistent manner with the scaling equation of state. We propose a new parameterization of the critical correlation length in terms of the same parametric variables (R, θ) used for the BEST EoS, consistent with the 𝜖-expansion. Additionally, we study how these parametrizations of the correlation length could be used to calculate critical cumulants, updating the early work of [1]. These will be useful for further comparison to estimates of out-of-equilibrium fluctuations in order to determine the magnitude of the observable fluctuations to be expected in heavy-ion collision experiments, in which the time spent near a critical point is short.

        1. C. Athanasiou, K. Rajagopal, M. Stephanov, “Using Higher Moments of Fluctuations and their Ratios in the Search for the QCD Critical Point,” Phys. Rev. D 82 (2010), 074008.
        2. M. Stephanov, “On the sign of kurtosis near the QCD critical point,” Phys. Rev. Lett. 107 (2011), 052301.
        3. P. Parotto, M. Bluhm, D. Mroczek, M. Nahrgang, J. Noronha-Hostler, K. Rajagopal, C. Ratti, T. Schaefer, and M. Stephanov, “QCD equation of state matched to lattice data and exhibiting a critical point singularity,”Phys. Rev. C 101 (2020), 034901.
        4. J.M. Karthein, D. Mroczek, A.R. Nava Acuna, J. Noronha-Hostler, P. Parotto et al., “Strangeness-neutral equation of state for QCD with a critical point,” Eur. Phys. J. Plus 136 (2021) 6, 621.
        5. D. Mroczek, A.R. Nava Acuna, J. Noronha-Hostler, P. Parotto, C. Ratti et al., “Quartic cumulant of baryon number in the presence of a QCD critical point,” Phys. Rev. C 103 (2021) 3, 034901.
        6. T. Dore, J.M. Karthein, I. Long, D. Mroczek, J. Noronha-Hostler et al., “Critical lensing and kurtosis near a critical point in the QCD phase diagram in and out-of-equilibrium,” arXiv:2207.04086.
        Speaker: Jamie Karthein (Massachusetts Institute of Technology)
      • 33
        Critical point fluctuations in heavy-ion collisions within molecular dynamics with expansion

        We analyze particle number fluctuations in the crossover region near the critical endpoint of a first-order phase transition in baryon-rich matter by utilizing microscopic molecular dynamics simulations of the classical non-relativistic Lennard-Jones fluid. We extend out previous studies by incorporating longitudinal collective flow to model the expansion dynamics in heavy-ion collisions.

        In heavy-ion experiments it is possible to observe fluctuations in the momentum space only, so we are concentrating our current research around this topic. Using as a beginning result of our previous article about the momentum space fluctuations without the collective flow, where the scaled variance appears to be close to the ideal gas without interaction, we apply shift in one of the space directions to the thermal momentum of the particles.

        The scaled variance of particle number distribution inside different coordinate and momentum space acceptances is computed through ensemble averaging and found to agree with earlier results obtained using time averaging, validating the ergodic hypothesis for fluctuation observables in considered system. The presence of a sizable collective flow is found to be essential for observing large fluctuations from the critical point in momentum space acceptances. We find that the enhancement of baryon number fluctuations due to critical point is visible at collision energies between 3 and 10 GeV in realistic rapidity space acceptances. We discuss our findings in the context of the ongoing measurements of proton number cumulants in heavy-ion collisions.

        Speaker: Volodymyr Kuznietsov (University of Houston)
      • 34
        Bayesian location of the QCD critical point: a holographic perspective

        We present the first prediction of a QCD critical point (CP) from a Bayesian analysis constrained by first principle results at zero baryon density. We employ the gauge/gravity duality to map QCD onto a theory of dual black holes. Predictions for the CP location in different realizations of the model overlap at one sigma. Even if many prior samples do not include a CP, one is found in nearly 100% of posterior samples, indicating a strong preference for a CP.

        Speaker: Claudia Ratti (University of Houston)
    • Track6-SmallSyst Londres 1 (Palais de la Musique et des Congrès)

      Londres 1

      Palais de la Musique et des Congrès

      Chairperson: Prabhat Pujahari (IIT Madras, India)

      Conveners: Maxime Guilbaud (SUBATECH), Maxime Guilbaud (SUBATECH)
      • 35
        Unraveling the origin of collectivity in high and low multiplicity pp and p--Pb collisions in ALICE at the LHC

        We investigate the possibility of a partonic phase in small systems by measuring the elliptic flow of mesons (π⁺⁻, K⁺⁻, K⁰) and baryons (p+$\bar{\rm p}$, Λ+Λ̅) in high-multiplicity p--Pb collisions at $\sqrt{s_{{\rm NN}}}$ = 5.02 TeV and pp collisions at $\sqrt{s}$ = 13 TeV measured by ALICE. The results show a grouping (with 1$\sigma$ significance) and splitting (with 5$\sigma$ confidence) behavior of v₂ at intermediate pt. This phenomenon, reminiscent of partonic flow in heavy-ion collisions, has been observed with such high precision for the first time in small collision systems. Comparison with the hydrodynamic model with hadronization via quark coalescence indicates the formation of a deconfined partonic medium in small systems at high multiplicity. We further extend these measurements down to the lowest possible multiplicity in pp collisions employing the largest pseudorapidity separation (5.0 < |$\Delta\eta$| < 6.0) to explore the limits to the formation of the collective medium and presence of partonic degrees of freedom in small systems.

        Speaker: Dr Debojit Sarkar (Wayne State University, US)
      • 36
        Collectivity in small systems with the ATLAS detector

        This talk presents the latest ATLAS measurements of collective phenomena in small collision systems, including pp collisions and Ultraperipheral collisions (UPC) of heavy ions. In pp collisions, presented measurements include flow decorrelations in rapidity for probing the longitudinal structure and study of the sensitivity of collective motion in pp collisions to the presence of jets, which aims to distinguish the role that semi-hard processes play in the origin of these phenomena. In UPCs, the measurement of charged hadron production is presented as a function of pseudorapidity and transverse momentum in different categories of event multiplicity. Together with previously measured elliptic flow coefficients, the yields and mean pT results are compared with calculations from DPMJET and hydrodynamic-based models. These comparisons enable detailed characterizations of photonuclear event properties, including the photon energy distribution and whether small QGP droplets may be formed.

        Speaker: Blair Daniel SEIDLITZ
      • 37
        Multiplicity Dependent Study of (Multi-)strange Hadrons in $d$+Au collisions using the STAR detector

        Strangeness enhancement has long been considered a signature of the quark-gluon plasma formation in heavy-ion collisions. Strangeness enhancement has also been observed in small systems at the LHC, but the underlying physics is not yet fully understood. This motivates studies of strange hadron production in small systems at RHIC, where the energy density of system is expected to be smaller than that at the LHC and therefore a hot and deconfined medium is less likely to be created. Investigating the multiplicity dependence of strange hadron production in small systems can naturally connect to peripheral heavy-ion collisions, and contribute to understanding the role of event multiplicity in strange hadron production. Study of rapidity asymmetry and nuclear modifiaction factors in $d$+Au collisions can also give insight on cold nuclear matter effects.

        In this talk, we will present new measurements of (multi-)strange hadrons ($K_S^0$, $\Lambda$, $\Xi$ and $\Omega$) in $d$+Au collisions at $\sqrt{\rm s_{\rm NN}}$ = 200 GeV, collected by STAR in 2016. We will analyze the multiplicity dependence of strange hadron transverse momentum ($p_{\rm{T}}$) spectra, $p_{\rm{T}}$-integrated yields dN/dy, average transverse momentum ($\langle p_{\rm{T}} \rangle$), and yield ratios to pions. We will also present nuclear modification factors and rapidity asymmetry for these particles. We will discuss implications of our measurements on the possible formation of a hot and deconfined medium and the origin of strangeness enhancement in small systems.

        Speakers: Ishu Aggarwal, Ishu Aggarwal (Panjab University Chandigarh)
      • 38
        Heavy flavor production and collectivity in high energy proton-proton collisions

        The creation of a quark-gluon plasma (QGP) is expected in ultrarelativistic heavy ion collisions. It came as a surprise that proton-proton collisions at ultrarelativistic energies show as well a "QGP-like" behavior and signs of the creation of a nearly perfect fluid, although the corresponding system size is not more than a few cubic femtometers. Even more surprisingly, also heavy flavor particles seem to be part of the fluid or at least interact with it. Recently, we investigated this "collective behavior" of heavy flavor in a quantitative way~[1], by employing the newly developed EPOS4HQ approach, which has been used to describe both heavy and light flavor hadrons in relativistic heavy ion collisions~[2,3]. In this talk, I will show the detail of the EPOS4HQ framework, which contains gluon splitting, flavor excitation, and flavor creation as elementary processes for the creation of heavy quarks. This allows us to disentangle initial state effects, those being due to interactions between charm quarks and plasma partons, and final state effects. Finally, I will show all observables, which may manifest collectivity, such as particle spectra, elliptic flow, baryon-to-meson ratios, and two-particle correlations, and compare the results with experimental data.


        Speakers: Pol Gossiaux (Subatech), pol bernard gossiaux (subatech)
      • 39
        Observation of hydrodynamic behavior with few strongly-interacting fermions: a zero-temperature small system puzzle

        Approaching zero temperature, a gas of strongly-interacting fermions undergoes a transition to a superfluid phase amenable to an ideal hydrodynamic description. At trillion-kelvin temperatures, hadronic matter melts into a quark-gluon plasma (QGP) that flows similarly as a near-perfect fluid. Collider experiments indicate that the signals of QGP formation are mysteriously persistent, emerging down to p-p collisions producing only a few dozen final-state hadrons. Here, we perform experiments to assess whether a similar behavior is displayed as well in small systems at the other end of the temperature spectrum.

        States of strongly-interacting ultra-cold fermions are released from elliptical harmonic traps to investigate the emergence of elliptic flow, a smoking-gun of collective behavior. Borrowing techniques from high-energy collisions [1], we study the build-up of momentum anisotropy in the elliptical clouds and the inversion of their initial aspect ratios. Elliptic flow is then observed for systems with as few as 10 fermions and in absence of any separation between microscopic and macroscopic scales [2], opening a new small system puzzle outside heavy-ion collisions. We discuss prospects for future cross-disciplinary research aimed at elucidating further the apparent hydrodynamic behavior of mesoscopic quantum gases.

        [1] Floerchinger et al., Phys.Rev.C 105 (2022) 4, 044908
        [2] Brandstetter et al., arXiv:2308.09699

        Speaker: Lars Heyen (Universität Heidelberg)
    • 10:10 AM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Track1-LF Room Madrid (Palais de la Musique et des Congrès)

      Room Madrid

      Palais de la Musique et des Congrès

      Convener: Domenico Elia (INFN Bari, Italy)
      • 40
        Testing CPT symmetry with multistrange baryons mass precision measurements with ALICE

        In any relativistic quantum field theory such as Quantum Chromodynamics or Electroweak theory, the interactions are invariant under the combined operation of Charge conjugation (C), Parity transformation (P) and Time reversal (T). One of the consequences of this (CPT) symmetry is that particles and their corresponding antiparticles must have exactly same mass. While the mass difference bewteen proton and antiproton has been measured to very high precision, the extension to (multi-)strange baryons domain still lacks precise measurements.
        The ALICE detector is optimized to reconstruct decays of multistrange baryons ($\Xi$ and $\Omega$). The collected data in pp at $\sqrt{s}$ = 13 TeV during the LHC Run 2 (almost two billion events) together with the particle identification capabilities of the ALICE detector allow to measure the mass of the multistrange hyperons and antihyperons with very high precision. In this contribution, the mass differences between $\Xi^{-}$ and $\overline{\Xi}^{+}$ and between $\Omega^{-}$ and $\overline{\Omega}^{+}$ will be presented, sensibly improving the precision obtained by averaging the results from previous experiments.

        Speaker: Romain Schotter
      • 41
        Scaling Properties of φ-Meson and Light Charged Hadron Production in Small and Large Systems at PHENIX

        Light hadrons are considerably produced in high-energy heavy-ion collisions and provide a wealth of information about properties of created QCD medium and reaction dynamics. These include, in particular, the implications of collective flow in small and large systems
        and the impact of recombination on baryon and strangeness enhancement. The system size dependence studies of different observable are crucial to investigate the properties of Quark Gluon Plasma and hadronization based on initial conditions of the collisions such as nuclear-overlap size, shape of nuclei, and nuclear modification of the parton-distribution functions.

        In this talk, we will present recently finalized measurements by PHENIX on the nuclear modification and elliptic flow of φ-meson in Cu+Au, and U+U collisions, and production of identified light charged hadron in small and large system size, p+Al, p/d/3He/Cu+Au, and U+U collisions [1] at RHIC energies as a function of centrality and transverse momentum. The tests of various empirical scaling, and interpretation of the results with respect to the current theoretical model calculations are provided for better understanding of the underlying processes.


        [1] N.J. Abdulameer et al. (PHENIX Collaboration), arXiv:2312.09827 [nucl-ex]

        Speaker: Dr Rachid Nouicer for the PHENIX Collaboration (Brookhaven National Laboratory)
      • 42
        Measuring the system size dependence of the strangeness production with ALICE

        Measurements of light-flavour particle production in small collision systems at the LHC energies have shown the onset of features (e.g. collective evolution, strangeness enhancement) that resemble what is typically observed in nucleus-nucleus collisions. These features were shown at the LHC to scale with the charged-particle multiplicity independently on the collision system and energy.
        New results on the (multi-)strange hadron production in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 and 5.36 TeV collected in the Run 2 and Run 3 of the LHC will be presented. These results are discussed in the context of recent measurements of light-flavour hadron production in pp collisions at $\sqrt{s}$ = 0.9 and 13.6 TeV collected by the ALICE experiment during Run 3 of the LHC. With the wealth of data collected with the ALICE upgraded detector, it is possible to bridge the gap in multiplicity between small and large systems, improving the measurement precision and exploring the lowest multiplicity region. The ratios between strange and non-strange hadron yields are measured in pp collisions up to charged-particle multiplicity values comparable to those reached in peripheral Pb–Pb collisions, providing insight into the collision system dependence of strangeness enhancement. Multiplicity, energy and system size dependencies are investigated, comparing with predictions from state-of-the-art models.

        Speaker: Roman Nepeivoda (Lund University)
      • 43
        Strangeness production in $pp$ and $p$Pb collisions at LHCb

        Strange hadron production provides information about the hadronization process in high-energy hadron collisions. Strangeness enhancement has been interpreted as a signature of quark-gluon plasma formation in heavy-ion collisions, and recent observations of strangeness enhancement in small collisions systems have challenged conventional hadronization models. With its forward geometry and excellent particle identification capabilities, the LHCb detector is well-suited to study strangeness production in a unique kinematic region. Recent studies of strangeness production with the LHCb detector will be presented, including measurements of strangeness enhancement in the charm- and beauty-hadron systems, as well as studies of hyperon polarization.

        Speaker: Clara Landesa Gomez
      • 44
        Studying (multi-)strange hadron angular correlation with associated particles and their production with event topology using the ALICE detector

        The angular correlation between (multi-)strange and associated identified hadrons is measured in pp collisions with the ALICE detector to give insight into the particle production mechanisms and balancing of quantum numbers at the microscopic level. These measurements are expected to be sensitive to whether strangeness is produced through string breaking or in a thermal production scenario. The results are compared to predictions from the string-breaking model PYTHIA 8, including tunes with baryon junctions and rope hadronisation enabled, the cluster hadronisation model HERWIG 7, and the core-corona model EPOS-LHC. In addition, the connection of strange hadron production to hard scattering processes and to the underlying event is also studied. For this purpose, the production of strange hadrons is also measured in each event in the direction of the highest-$p_{\rm T}$ particle (trigger particle), related to hard scattering processes, and in the direction transverse to it, associated with the underlying event, in pp collisions.

        Speaker: Chiara De Martin
    • Track2-HF&Q Room Rome (Palais de la Musique et des Congrès)

      Room Rome

      Palais de la Musique et des Congrès

      Convener: Marianna Mazzilli (University and INFN of Bari)
      • 45
        First $D^0+\overline{D^0}$ measurement in heavy-ion collisions at SPS energies with NA61/SHINE

        The measurement of open charm meson production provides a tool for the investigation of the properties of the hot and dense matter created in nucleus-nucleus collisions at relativistic energies. In particular, charm mesons are of vivid interest in the context of the study of the nature of the phase-transition between confined hadronic matter and the quark-gluon plasma. Recently, the experimental setup of the NA61/SHINE experiment was upgraded with the high spatial resolution Vertex Detector which enables the reconstruction of secondary vertices from open charm meson decays.

        In this presentation the first $D^0$ meson yields at the SPS energy regime will be shown. The analysis used the most central 20% of Xe+La collisions at 150A GeV/c from the data set collected in 2017. This allowed the estimation of the corrected yields (dN/dy) for $D^0+\overline{D^0}$ via its $\pi^{+/-} + K^{-/+}$ decay channel at mid-rapidity in the center-of-mass system. The results will be compared and discussed in the context of several model calculations including statistical and dynamical approaches.

        Speaker: Anastasia Merzlaya (Universitetet i Oslo)
      • 46
        The role of strangeness in heavy-quark hadronisation from small to large collision systems with ALICE

        Production measurements of strange hadrons originating from the hadronisation of charm quarks (prompt) and from beauty-hadron decays (non-prompt) offer a unique tool to study the heavy-quark hadronisation across different collision systems. In proton-proton (pp) and p–Pb collisions, they enable quantifying the fragmentation of heavy quarks to strange heavy-flavour hadrons relative to that of heavy-flavour hadrons without strange valence quark. These measurements also provide important tests for perturbative QCD-based calculations and the possible presence of cold nuclear-matter effects. In Pb–Pb collisions, the production of heavy-flavour hadrons with strange-quark content is sensitive to the hadronisation mechanisms of charm and beauty quarks in the quark–gluon plasma (QGP) and to final-state effects. If a fraction of heavy quarks hadronises via recombination with light-flavoured quarks in the medium, the production of heavy hadrons with strange-quark content is expected to be enhanced compared to that of non-strange hadrons, due to the abundant production of (anti)strange quarks in heavy-ion collisions compared to pp and p–Pb collisions.

        This contribution discusses the final results of the ALICE Collaboration obtained by measuring strange D mesons in pp, p–Pb, and Pb–Pb collisions collected during the LHC Run 2. It reports the charm-quark fragmentation fraction to strange D mesons in pp and p–Pb collisions. The first measurement of the production of orbitally excited charm-strange mesons in pp collisions is also reported. Additionally, the production measurements of prompt $\mathrm{D_s}^+$ mesons are compared to those of non-strange mesons across the different collision systems, along with the measurement of non-prompt $\mathrm{D_s}^+$ mesons in heavy-ion collisions. Lastly, the first studies of strange and non-strange D mesons using the large data sample of pp collisions at $\sqrt{s} = 13.6$ TeV harvested from the start of LHC Run 3 are presented.

        Speaker: Mattia Faggin (CERN)
      • 47
        Open heavy flavor production at LHCb

        The LHCb experiment is a dedicated heavy-flavor experiment at the LHC and is uniquely well-suited to studying heavy-flavor production in heavy-ion collisions. Open heavy-flavor production studies at LHCb provide strong constraints on nuclear parton densities and probe the hadronization process in the hot, dense, nuclear media produced in heavy-ion collisions. Recent measurements of heavy-flavor production in heavy-ion collisions with the LHCb detector will be presented, including studies of charm and beauty baryon production.

        Speaker: Jianqiao Wang
      • 48
        A potential approach to the X(3872) thermal behaviour

        We study the potential of X(3872) at finite temperature in the Born-Oppenheimer approximation under the assumption that it is a tetraquark. We argue that, at large number of colors, it is a good approximation to assume that the potential consists in a real part plus a constant imaginary term. The real part is then computed adapting an approach by Rothkopf and Lafferty and using as input lattice QCD determinations of the potential for hybrids. This model allows us to qualitatively estimate at which temperature range the formation of a heavy tetraquark is possible, and to propose a qualitative picture for the dissociation of the state in a medium. Our approach can be applied to other suggested internal structures for the X(3872) and to other exotic states.

        Speaker: Miguel Angel Escobedo Espinosa
      • 49
        Flavor hierarchy of parton energy loss in quark-gluon plasma from a Bayesian analysis

        The quenching of light and heavy flavor hadrons in relativistic heavy-ion collisions probes the color and flavor dependences of parton energy loss through a color-deconfined quark-gluon plasma (QGP), and thus offers an important test of QCD-based calculation at extremely high density and temperature. By combining a next-to-leading order perturbative QCD calculation of parton production, a general ansatz of parton energy loss functions and parton fragmentation functions, we calculate the nuclear modification of various hadron species -- charged hadrons, $D$ mesons and $B$-decayed $J/\psi$ -- over a wide transverse momentum regime. Comparing our calculations to the experimental data using the Bayesian statistical analysis, we perform a first simultaneous extraction of the energy loss functions of gluons ($g$), light quarks ($q$), charm quarks ($c$) and bottom quarks ($b$) inside the QGP. We find that the average parton energy loss at high energies follows the expected hierarchy of $\langle \Delta E_g \rangle > \langle \Delta E_q \rangle \sim \langle \Delta E_c \rangle > \langle \Delta E_b \rangle$, while the parton energy loss distribution can further test the QCD calculations of parton interaction with the dense nuclear matter.
        We also find that the reduction of experimental uncertainties can significantly improve the precision of the extracted parton energy loss functions inside the QGP.

        [1] Wen-Jing Xing, Shanshan Cao and Guang-You Qin, Phys.Lett.B 850 (2024) 138523,arXiv:2303.12485
        [2] Wen-Jing Xing, Shanshan Cao, Guang-You Qin and Hongxi Xing,Phys.Lett.B 805 (2020) 135424, arXiv:1906.00413

        Speaker: Wen-Jing Xing (Shandong University)
    • Track4-Bulk&Phase: 5 talks Room Bruxelles (Palais de la Musique et des Congrès)

      Room Bruxelles

      Palais de la Musique et des Congrès

      Convener: Stefan Floerchinger (Friedrich-Schiller-Universität Jena)
      • 50
        QCD equation of state, critical point and hydrodynamics of fluctuations

        Recent theory developments aimed at mapping QCD phase diagram and the search for the critical point in heavy-ion collisions will be discussed. These include understanding of QCD equation of state and the universal properties of fireball trajectories near the critical point, hydrodynamic description of non-Gaussian fluctuations and their freeze-out consistent with conservation laws.

        Speaker: Mikhail Stephanov (University of Illinois at Chicago)
      • 51
        Modeling spinodal decomposition in a rapidly expanding fluid

        The QCD phase diagram is expected to have a first order phase transition at high baryon densities which will give rise to effects like spinodal decomposition and nucleation in the cooling quark gluon plasma. We expect to probe this region beyond the critical point at the Beam Energy Scan Program at RHIC and the upcoming experiments at the Facility for Antiproton and Ion Research (FAIR). It is crucial to include these effects in our simulations to explain the data. We derive the equations governing spinodal decomposition in an expanding hydrodynamic system. The equations account for surface effects between different phases. The equation of state is extended to the metastable region by interpolation. We numerically solve these equations for a 1D expanding Bjorken fluid and discuss the effects of phase separation.

        Speaker: Mayank Singh (Vanderbilt University)
      • 52
        Exploring the QCD phase diagram with collective flow at STAR

        Directed and elliptic flow ($v_{1}$, $v_{2}$) are sensitive to the dynamics of heavy-ion collisions and the equation of state (EoS) of the medium. The $v_1$ slope with rapidity ($dv_1/dy$) at mid-rapidity of net-baryons is expected to be sensitive to the first-order phase transition. Studying the flow harmonics for various identified particles at different collision energies provides insights into the medium going through QCD phase transition. In particular, (multi-) strange hadrons with small hadronic cross-sections are cleaner probes of the early stages of heavy-ion collisions. A comprehensive study of light and (multi-) strange hadrons provides valuable insights into the subsequent stages of the medium evolution.

        In this talk, the measurements of $v_1$ and $v_2$ for both light and (multi-) strange hadrons at $\sqrt{s_{NN}}$ = 3.0 - 19.6 GeV, with the enhanced capabilities of the STAR detector and increased statistics from the second phase of the RHIC beam energy scan (BES-II) program, will be presented. The centrality dependence of anisotropic flow and the test of number of constituent quark (NCQ) scaling will be shown. Also, the energy and centrality dependence of $v_1$ slope and $p_T$-integrated $v_2$ will be presented. The data will be compared with different model calculations, and the inferences on the QCD phase structure and EoS of nuclear matter in the high baryon density region will be discussed.

        Speakers: Shusu Shi, Prof. Shusu Shi (Central China Normal University)
      • 53
        Probing the speed of sound in QGP with multi-particle $[p_{\rm T}]$ cumulants in ALICE

        The speed of sound squared, $c_s^2$, one of the properties of the quark-gluon plasma (QGP) connected to the QCD equation of state, can be extracted from ultra-central heavy-ion collisions, where the medium mostly maintains a fixed size and fluctuations in the initial state and thermal fluctuations dominate. We present the first ALICE measurements of the event-by-event mean transverse momentum, $\langle[p_\mathrm{T}]\rangle$, in particular its average and higher-order fluctuations as a function of multiplicity using particle spectra and multi-particle $\langle[p_\mathrm{T}]\rangle$ cumulant techniques, in ultra-central Pb--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV. The pronounced rise in $\langle[p_\mathrm{T}]\rangle$ and the sudden transition in higher-order fluctuations at high multiplicities are used to extract the speed of sound in QGP, $c_s^2$, and to probe the thermalisation of the QGP, respectively. Our approach yields valuable insights into the thermalized nature of the deconfined state resulting from heavy-ion collisions, contributing to a deeper understanding of the QCD equation of state.

        Speaker: Emil Gorm Nielsen
      • 54
        Measuring the speed of sound in the QGP with the CMS experiment

        A hot and dense matter exhibiting collective flow behavior with almost no viscous dissipation has been discovered in ultrarelativistic nuclear collisions. To experimentally constrain the equation of state of this matter, we present a measurement of its speed of sound using head-on lead-lead collision data collected by the CMS experiment at a center-of-mass energy per nucleon pair of 5.02 TeV. The measurement uses an analysis of the observed charged multiplicity dependence of the average particle transverse momentum in ultracentral events (impact parameter of nearly zero), a variable which probes the system temperature as a function of entropy density at a fixed volume. Results are compared with hydrodynamic simulations and lattice QCD predictions of the equation of state at high temperatures and small chemical potential. Implications for the exploration of the QCD phase structure and the search for a critical point are discussed.

        Speaker: Michael Murray
    • Track6-SmallSyst Room Londres 1 (Palais de la Musique et des Congrès)

      Room Londres 1

      Palais de la Musique et des Congrès

      Chairperson: Prabhat Pujahari (IIT Madras, India)

      Convener: Alice Ohlson (Lund University)
      • 55
        Tantalizing Structure in Long Range Correlations in High Multiplicity e+e- Collisions And Fourier Decomposition Using Archived ALEPH Data at 91-209 GeV

        We present measurements of two-particle angular correlations of charged particles emitted in high-energy $e^{+}e^{-}$ collisions using data collected by the ALEPH detector at LEP between 1992 and 2000. The correlation functions are measured over a wide range of pseudorapidity and azimuthal angle as a function of charged particle multiplicity. Previous measurement with LEP1 data at 91 GeV shows no significant long-range correlations in lab coordinate or thrust coordinate analyses, with associated yield distributions in agreement with predictions from the archived PYTHIA v6.1 event generator. Higher collision energy LEP2 data allows access to higher event multiplicity and additional production channels beyond the $Z\to q\bar{q}$ process. The highest multiplicity bin suggests an intriguing deviation from archived MC and implies the potential to search for collective phenomena in small systems. This measurement is pushing the studies of long-range correlation to the smallest collision system limit. It includes the first flow coefficient measurement and a Fourier decomposition analysis in $e^{+}e^{-}$ collisions to quantify the anisotropy in the azimuthal two-particle correlation as a function of charged particles' transverse momentum. It is also compared with modern MC generators. This work supplements our understanding of small-system references to long-range correlations observed in proton-proton, proton-nucleus, and nucleus-nucleus collisions.

        Speaker: Austin Baty (UIC)
      • 56
        Signals of initial state quantum entanglement in relativistic particle collision

        I will show thermodynamic entropy calculations based on charged particle multiplicity data from proton-proton collisions measured by ALICE at the LHC in comparison to entanglement entropy calculations based on initial state gluon distributions. The relative agreement of these distributions can be quantified by studying their higher order cumulants. The commonalities between the initial and final state suggest
        that entanglement could be a possible source for the seemingly thermal and collective behavior in small systems. I will pose the question on when such a picture could and will break down due to decoherence of the initial state. I will also show that rather simple additional final state measurements should be sensitive to gluon saturation, in particular when properly binned in rapidity space.

        Speaker: Rene Bellwied (University of Houston)
      • 57
        Particle production as a function of charged-particle flattenicity in small collision systems with ALICE

        Event classifiers based either on the charged-particle multiplicity or on event topologies, such as spherocity and underlying event activity, have been extensively used in proton-proton (pp) collisions by the ALICE Collaboration at the LHC. These event classifiers became important tools since the observation of fluid-like behavior in high multiplicity pp collisions as for example radial and anisotropic flow. Furthermore, the study as a function of the charged-particle multiplicity allowed for the discovery of strangeness enhancement in high-multiplicity pp collisions. However, one drawback of the multiplicity-based event classifiers is that requiring a high charged-particle multiplicity biases the sample towards hard processes like multijet final states. These biases blur the effects of multi-parton interactions (MPI) and make it difficult to pinpoint the origins of fluid-like effects.

        This contribution exploits a new event classifier, the charged-particle flattenicity, defined in ALICE using the charged-particle multiplicity estimated in 2.8 < $\eta$ < 5.1 and −3.7 < $\eta$ < −1.7 intervals. New final results on the production of pions, kaons, protons, and unidentified charged particles at midrapidity (|$\eta$| < 0.8) as a function of flattenicity in pp collisions at $\sqrt{s}$ = 13 TeV will be discussed. It will be shown how flattenicity can be used to select events more sensitive to MPI and less sensitive to final-state hard processes. All the results are compared with predictions from QCD-inspired Monte Carlo event generators such as PYTHIA and EPOS. Finally, an outlook on using the flattenicity estimator using Run3 data will be shown.

        Speaker: Antonio Ortiz
      • 58
        Using Multivariate Cumulants to Constrain the Initial State in XeXe and PbPb Collisions at the CMS Experiment

        Xenon (Xe) nuclei are deformed and have a nonzero quadrupole moment, whereas lead (Pb) nuclei are considered spherical in shape. The study of XeXe collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{_{\mathrm{NN}}}} = 5.44$ TeV opens up a window to study nuclear deformation using the CMS experiment. When compared to the Run 3 PbPb data at a center-of-mass energy per nucleon pair of $\sqrt{s_{_{\mathrm{NN}}}} = 5.36$ TeV, which is very close to that of XeXe, one can explore the dependence of the Fourier flow coefficients on the size and initial-state geometry of the colliding system. For the first time, correlations between higher order moments of two as well as three flow harmonics ($v_\mathrm{2}$ to $v_\mathrm{6}$, up to orders 8 or 10) are measured in XeXe and PbPb collisions as a function of collision centrality. These new measurements have been calculated with multiparticle mixed harmonic cumulants using charged particles in the pseudorapidity region $|\mathrm{\eta}| < 2.4$ and the transverse momentum range $0.5 < p_\mathrm{T} < 3.0$ GeV /c. The results have also been compared to theoretical model predictions provided by the IP-Glasma+MUSIC+UrQMD model, which helps us to constrain the initial-state deformation parameters of Xenon nuclei. Furthermore, it has been shown that both hydrodynamic probes $\frac{\mathrm{v_\mathrm{2}\{6\}-v_\mathrm{2}\{8\}}}{\mathrm{v_\mathrm{2}\{4\}-v_\mathrm{2}\{6\}}}$ and $\frac{\mathrm{v_\mathrm{2}\{8\}-v_\mathrm{2}\{10\}}}{\mathrm{v_\mathrm{2}\{6\}-v_\mathrm{2}\{8\}}}$ are centrality dependent, explained by introducing newly measured higher order moments in the Taylor expansion of the corresponding generating function of the cumulants. The higher order moments, skewness, kurtosis, and the superskewness (5th moment) are expressed through the $v_\mathrm{2}\{2k\}$ (k = 1, ..., 5) harmonics and are shown as a function of collision centrality. Overall, these studies will significantly constrain initial-state model parameters and give us a better understanding of the transport properties of the quark-gluon plasma created in heavy ion collisions at the LHC.

        Speaker: Aryaa Dattamunsi
      • 59
        Multiplicity dependent and inside-jet measurement of light neutral mesons in pp collisions with ALICE

        This talk presents measurements by the ALICE Collaboration of neutral $\pi^0$, $\eta$, and $\omega$ meson production in proton-proton collisions at $\sqrt{s}$ = 13 TeV. Such measurements can constrain the proton parton distribution functions (PDF) and fragmentation functions (FF), and provide input for background corrections of direct photon and dileption analyses. Measurements of $\pi^0$ and $\eta$ meson distributions within and outside of reconstructed jets are reported, which constrain meson FFs. Distributions of inclusive meson production in multiplicity-selected pp collisions are also reported. Phenomena that are characteristic of quark-gluon plasma (QGP) formation, notably strangeness enhancement and the presence of collective flow, have been observed previously in high-multiplicity pp collisions. These new measurements provide additional insight into particle production and hadron chemistry, and the formation of the QGP in small systems.

        Speaker: Joshua Konig
    • 12:30 PM
      Lunch break Room Étoile

      Room Étoile

    • Track2-HF&Q Room Rome (Palais de la Musique et des Congrès)

      Room Rome

      Palais de la Musique et des Congrès

      Convener: Roberta Arnaldi (INFN Torino)
      • 60
        Quarkonium production in pp and heavy-ion collisions

        Quarkonium is considered as a probe, which may expose properties of the expanding QGP, produced in ultra-relativistic heavy-ion collisions. The theoretical description of the formation and the propagation of such a bound state of $c\bar c$ or $b\bar b$ quark-antiquark pairs is a challenging task.

        Here we propose a model, which realizes quarkonium production in pp and AA collisions with help of quantal density matrices. This identification is embedded in a quantum-mechanical description of heavy quark propagation and interaction.

        The Quarkonium production is realized in two steps:
        1) The heavy quark production in pp collisions is given by the PYTHIA event generator;
        2) The formation of a quarkonium from a $c\bar c$ or $b\bar b$ pair is described by the Wigner projection in momentum space with a spatial separation based on the uncertainty principle~\cite{Song:2017phm} . With this formalism we find a good agreement with the experimental rapidity and transverse momentum distributions for the ground states as well as for the excited states of $c\bar c$ and $b\bar b$ mesons in pp collisions from RHIC to LHC energies.

        In a second step we test whether the quantal Remler formalism to describe bound state production in an expanding medium can be realized in a Monte Carlo approach for a QGP. For this study we use a box of thermalized QGP and investigate the time evolution of the c and $\bar c$, which are initially not in equilibrium with the QGP, either by localizing them in a smaller box and/or by giving them initially a different temperature. Comparing numerical and analytical results we demonstrate that, if there is no potential interaction between the c and $\bar c$, the original Remler formalism has to be modified by introducing a spatial diffusion rate to compensate for the expansion of the system~[1].

        As a third step we study bottonium production in heavy-ion collisions, where the properties of bottonium in a QGP, the dissociation temperature and the temperature-dependant radius, are obtained by solving the Schr\"{o}dinger equation with the free energy from lattice QCD calculations as heavy quark potential. The elastic scattering of heavy (anti)quarks with light plasma partons is described by the dynamical quasi-particle model (DQPM). %It turns out that the bottonium is too much suppressed during the expansion as compared to the experimental results for Pb+Pb collisions at $\sqrt{s_{\rm NN}}=$ 5.02 TeV.
        %To take into account the small size and color neutrality of bottomonium, we introduce a suppression of its scattering rate in a QGP to 10 \% of bottom and antibottom quarks.
        %Such a suppression of the scattering rate brings the centrality dependence of the yields as well as the rapidity and transverse momentum distributions to a good agreement with the experimental findings~[2].
        Considering that the two (anti)bottom quarks interact independently with QGP partons - as in the Remler formalism - and underestimate bottomonium yield, color neutrality has to be taken into account for agreement with the experimental results~[3].

        [1] T.~Song, J.~Aichelin and E.~Bratkovskaya, Phys. Rev. C 96, no.1, 014907 (2017).
        [2] T.~Song, J.~Aichelin and E.~Bratkovskaya, Phys. Rev. C 107, no.5, 054906 (2023).
        [3] T.~Song, J.~Aichelin, J.~Zhao, P.~B.~Gossiaux and E.~Bratkovskaya,
        Phys. Rev. C 108, no.5, 054908 (2023).

        Speaker: Dr Taesoo Song
      • 61
        Quarkonium dynamics in the quantum Brownian regime with non-abelian quantum master equations

        Being able to deal with the most acurate methods to describe the $Q\bar Q$ evolution in a Quark Gluon Plasma is a prerequisite to match the precise quarkonium measurements of all URHIC experiments. Following our recent work [1], we present exact numerical solutions in a one-dimensional setting of quantum master equations previously derived in [2].

        We focus on the dynamics of a single $Q\bar Q$ pair in a Quark-Gluon Plasma in thermal equilibrium, in the so-called quantum Brownian regime where the temperature of the plasma is large in comparison with the spacing between the energy levels of the $Q\bar Q$ system. The one-dimensional potential used in the calculations [2] has been adjusted so as to produce numbers that are relevant for the phenomenology of the charmonium.

        The equations are solved using different initial states and medium configurations. Various temperature regimes are studied and the effects of screening and collisions thoroughly analyzed. Distinctive features of the $Q\bar Q$ evolution with the quantum master equations are presented. Some phenomenological consequences are addressed by considering evolutions of a single $b\bar b$ in both Bjorken scenario and EPOS4 temperature profiles.

        Semiclassical approximation has been recently used [1,4] to describe charmonium production in URHIC, where many $c\bar c$ are implied. Obtaining an estimate of the systematic error attached to this approximation is of crucial importance to assess the agreement with experimental data. In the second part of the talk, we investigate the accuracy of the SC approximation by benchmarking the corresponding evolutions on the exact solutions derived with the QME for the case of a single $c\bar c$ pair.

        1. S. Delorme et al., arxiv 2402.04488
        2. J.-P. Blaizot and M.A. Escobedo, JHEP06(2018)034
        3. R. Katz, S. Delorme, P.-B. Gossiaux, Eur. Phys. J. A (2022) 58:198
        4. D.Y. Arrebato Villar et al., Phys.Rev.C 107 (2023) 5, 054913

        Speaker: Stéphane Delorme (IFJ PAN)
      • 62
        Observation of double J/$\psi$ production in pPb collisions with CMS

        The first observation of the simultaneous production of two $\rm{J}/\psi$ mesons in proton-nucleus collisions will be presented. The analysis is based on a data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16 TeV by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 174.6 $\rm{nb}^{-1}$. The $\rm{J}/\psi$ mesons are reconstructed in their $\mu^+\mu^-$ decay channel for transverse momenta $p_{\rm{T}} > 6.5$ GeV and rapidity $|y| < 2.4$. The measured inclusive fiducial cross section $\sigma(\rm{pPb} \to \rm{J}/\psi \rm{J}/\psi + X)$ will be compared to perturbative quantum chromodynamics predictions at next-to-leading-order accuracy, including nuclear parton densities effects, for the production of two $\rm{J}/\psi$ mesons in single- (SPS) and double- (DPS) parton scatterings. A fit of the data to the expected $\rm{pPb} \to \rm{J}/\psi \rm{J}/\psi + X$ SPS and DPS kinematic distributions of the two $\rm{J}/\psi$ mesons will provide new constraints on the effective DPS cross section of $\sigma_{\text{eff}}$, related to the transverse distribution of partons in the proton.

        Speaker: Stefanos Leontsinis
      • 63
        Investigating the interplay between initial hard processes and final-state effects measuring prompt and non-prompt J/$\psi$ with ALICE

        Quarkonium production in high-energy hadronic collisions is sensitive to both perturbative and non-perturbative aspects of quantum chromodynamics (QCD) calculations. In fact, the production of the heavy-quark pair is described by perturbative QCD while the formation of the bound state is a non-perturbative process, treated in different ways by available theoretical models. Charmonia cross section can be split into a prompt component, corresponding to the quarkonia directly produced by the charm (anti-charm) quarks, and a non-prompt one, corresponding to the quarkonia originating from the decay of beauty hadrons. The latter can be identified experimentally thanks to its displaced topology and plays an important role in the estimation of the beauty-hadron production cross section. Moreover, non-prompt charmonia is also a valuable tool to investigate the properties of the strongly interacting medium produced in ultra-relativistic heavy-ion collisions. In particular, $J/\psi$ produced in the decay of beauty hadrons can be used to study the mass dependence of heavy-quarks in-medium energy loss mechanism. In this contribution the recent measurement of prompt and non-prompt $J/\psi$ carried out by the ALICE Collaboration in pp and Pb-Pb collisions at midrapidity (|$y$| < 0.8), at $\sqrt{s}$ = 13 TeV and $\sqrt{s_{\rm {NN}}}$ = 5.02 TeV respectively, will be presented. Moreover, thanks to the installation of the new muon forward tracker (MFT), the prompt/non-prompt charmonia separation will be possible in LHC Run 3 also at forward rapidity (2.5 < $y$ < 4). The status of the new measurements at $\sqrt{s}$ = 13.6 TeV will be also presented and compared with the existing measurements and the available models.

        Speaker: Maurice Coquet
      • 64
        Detailed study of the production of $\Upsilon$ mesons in PbPb collisions with CMS

        One of the fundamental aspects of the formation and interaction of heavy quark bound states in the quark-gluon plasma is the amount of their suppression, expected to be stronger for quarkonia with smaller binding energies. Indeed, past results show a significant suppression of $\Upsilon\mathrm{(1S)}$ mesons in heavy ion collisions, with $\Upsilon\mathrm{(2S)}$ mesons being even more suppressed. However, for the $\Upsilon\mathrm{(3S)}$ meson, only upper limits have been reported so far. At the same time, features like polarization of quarkonia or feed-down contributions from excited states remain to be assessed. In this talk, we report the observation of the $\Upsilon\mathrm{(3S)}$ meson and a detailed study of the production of $\Upsilon$ mesons in lead-lead collisions recorded by CMS. For the first time, the nuclear modification factor has been extended to the strongly suppressed $\Upsilon\mathrm{(3S)}$ state. The results are compared with model calculations describing the dynamics of quarkonia in a hot environment, whereas future prospects are shown too.

        Speaker: Prabhat Ranjan Pujahari
      • 65
        Recent conventional and exotic charmonia results from LHCb

        Quarkonia production in hadronic collisions is an important experimental observable that sheds light on the heavy quark interaction with the nuclear medium. While the bound quarkonium states undergo dissociation and recombination in PbPb collisions, in $p$Pb collisions they can suffer from a combination of initial and final state effects such as shadowing and comover breakup. With high statistics from $pp$ and $p$Pb datasets, and excellent vertexing capabilities allowing separation of the prompt and $b$-decay components, LHCb performs precision measurements of J/$\psi$, $\psi(2S)$, and, for the first time at the LHC, $\chi_{c}$ production and modification. We will discuss these results, along with the first measurement of the nuclear modification factor of the exotic hadron X(3872), in context with recent model calculations.

        Speaker: Youen Kang
    • Track4-Bulk&Phase: 6 talks Room Bruxelles (Palais de la Musique et des Congrès)

      Room Bruxelles

      Palais de la Musique et des Congrès

      Convener: Anar Rustamov (GSI Helmholtzzentrum für Schwerionenforschung GmbH)
      • 66
        Simulating collectivity in dense baryon matter with multiple fluids

        Fluid-dynamical modelling of heavy-ion collisions in the region of RHIC Beam Energy Scan (BES) and FAIR experiments poses notable challenges. Contraction of the incoming nuclei is much weaker, which results in a long inter-penetration phase and a complex initial-state geometry. Conventional hydrodynamic models, where the fluid phase starts at a fixed proper time τ0, therefore miss the compression stage of the collision. Hence, they miss the key sensitivity to the EoS of the dense medium.
        We present a novel multi-fluid approach to simulate heavy-ion collisions in the region of RHIC BES and FAIR. In our approach, we circumvent the issue above by representing the incoming nuclei as two cold, baryon-rich fluids with appropriate energy and baryon densities. The newly produced matter is represented by a third baryon-free fluid, which is generated by the friction between the two colliding fluids. Our MUlti Fluid simulation for Fast IoN collisions (MUFFIN) model is implemented from scratch using a versatile 3+1 dimensional relativistic viscous hydrodynamic code vHLLE. We present benchmark calculations for Au-Au collisions at different RHIC BES energies, discuss the challenges in constructing the approach, and present a study [2] of flow and hyperon polarization observables at RHIC BES energies in MUFFIN. We discuss underlying vorticity development in multi-fluid approach, hyperon - anti-hyperon splitting, and compare our results to the recent data for hyperon polarization from HADES experiment at GSI, and a measurement from fixed-target program at RHIC, in addition to previous measurements within RHIC BES program. We examine directed flow observable at different collision energies, and show its equation-of-state dependence and the effects of final-state hadronic cascade, in a full-fledged dynamical model.

        [1] Jakub Cimerman, Iurii Karpenko, Boris Tomášik, and Pasi Huovinen, Phys. Rev. C 107, 044902 (2023)
        [2] Iu. Karpenko, J. Cimerman, arXiv:2312.11325

        Speaker: Iurii Karpenko (Czech Technical University in Prague)
      • 67
        Bayes-DREENA for QGP parameter inference from unified high and low-pt data

        Abstract: High-pt theory and data are conventionally utilized to examine interactions of high-pt partons with the Quark-Gluon Plasma (QGP). In contrast, bulk QGP properties are typically inferred from low-pt data and models. Our approach unifies these two domains through a finite-temperature dynamical energy loss DREENA framework, enabling a comprehensive assessment of QGP properties using both high-pt and low-pt data. We will demonstrate how the method can constrain the early evolution of the QGP and analyze the temperature dependence of the shear viscosity to entropy density ratio. By incorporating Bayesian inference within the DREENA framework, we show that using high-pt data jointly with low-pt data leads to parameter distributions within the bounds of those inferred only from low-pt data but are much better constrained. Thus, integrating DREENA within a formal statistical framework (Bayes-DREENA) allows more accurate inferences of QGP properties and utilizes a wide range of available data.

        Speaker: Magdalena Djordjevic (Institute of Physics Belgrade, Serbia)
      • 68
        Dependences of directed flow on the net electric charge, strangeness, and baryon number from quark coalescence

        Recently the rapidity-odd directed flow $v_1$ of produced hadrons has been studied [1]. Seven hadron species, $K^{-}$, $\phi$, $\bar{p}$, $\bar{\Lambda}$, $\bar{\Xi}^{+}$, $\Omega^{-}$ and $\bar{\Omega}^{+}$, have been used to construct multiple hadron sets with a small mass difference but given difference in the net electric charge ($\Delta q$) and strangeness ($\Delta S$) between the two sides. A nonzero directed flow difference $\Delta v_1$ has been proposed as a consequence of the electromagnetic field produced in relativistic heavy ion collisions [1,2],especially if $\Delta v_1$ increases with $\Delta q$.

        In this study [3], we examine the consequence of quark coalescence on $\Delta v_1$ of the hadron sets. We point out that quark coalescence leads to $\Delta v_1 = c_q \Delta q + c_S \Delta S$; therefore, in general $\Delta v_1 \neq 0$ for a hadron set with nonzero $\Delta q$ and/or $\Delta S$. The coefficients, $c_q = v_{1,\bar d} - v_{1,\bar u}$ and $c_S$ that contains $v_{1,\bar s} - v_{1,s}$, reflect the $v_1$ difference of produced quarks, which may be caused by the strong interaction and/or the electromagnetic field. Equivalently, one can write $\Delta v_1 = c_q \Delta q + c_B \Delta B$ that involves the difference in the net-baryon number ($\Delta B$), where quark coalescence gives $c_B=-3c_S$. We then propose two methods to extract the coefficients for the $\Delta q$- and $\Delta S$-dependences of $\Delta v_1$ (or the $v_1$ slope difference $\Delta v_1^\prime$).

        [1] A.I. Sheikh, D. Keane, P. Tribedy, Phys. Rev. C 105 (2022) 014912.
        [2] STAR Collaboration, arXiv:2304.02831.
        [3] K. Nayak, S. Shi, Z. W. Lin, Phys. Lett. B 849 (2024) 138479.

        Speaker: Prof. Zi-Wei Lin (East Carolina University)
      • 69
        Measurement of charge-dependent directed flow in STAR Beam Energy Scan (BES-II) Au+Au and U+U Collisions

        An ultra-strong magnetic field (B ≈ $\mathrm{10^{18}}$ Gauss) is anticipated during the early stages of heavy ion collisions. Such a strong magnetic field holds significant importance in QCD, including understanding topology of QCD vacuum, QCD phase transition, and nucleon structure. The directed flow or the first harmonic flow coefficient ($\mathrm{v}_1$), serves as a powerful tool not only for detecting the magnetic field but also for understanding its effects in the Quark-Gluon Plasma (QGP) medium (such as electrical conductivity). Additionally, $\mathrm{v}_1$ can capture information from the initial geometry of the system and also offer means to understand baryon transport. Recently, the STAR collaboration reported a substantial splitting of directed flow between positively and negatively charged identified particles in peripheral Au+Au and isobar (Ru+Ru and Zr+Zr) collisions. These results are consistent with the dominance of Faraday induction and Coulomb effect from the initial strong magnetic field [1].

        In this presentation, we shall discuss the rapidity dependence of $\mathrm{v}_1$ and d$\mathrm{v}_1$/dy for $\mathrm{\pi}^{\pm}$, $\mathrm{K}^{\pm}$ and p ($\bar{\mathrm{p}}$) in Au+Au collisions at 7.7, 11.5, 14.6, and 19.6 GeV from Beam Energy Scan Phase-II, as well as in U+U collisions at 193 GeV measured by the STAR experiment. The $\mathrm{v}_1$ values will be reported as a function of transverse momentum, rapidity, and centrality. Additionally, the d$\mathrm{v}_1$/dy and the charge dependent difference, $\Delta d\mathrm{v}_1$/dy, of identified particles in U+U collisions will be compared to those in Au+Au and isobar (Ru+Ru and Zr+Zr) collisions. These findings will offer further insights into the initial electromagnetic field as well as baryon transport at various system sizes and beam energies.

        [1]. STAR Collaboration, arXiv: 2304.03430

        Speaker: Muhammad Farhan Taseer
      • 70
        Dynamics of the chiral critical point in QCD, diffusion coefficient in Model G

        We present a detailed study of the finite momentum dynamics of the
        $O(4)$ critical point of QCD, which lies in the dynamic universality class of Model G. The critical scaling of the model is analyzed in multiple dynamical channels. For instance, the finite momentum analysis allows us to precisely extract the pion dispersion curve below the critical point. The pion velocity is in striking agreement with the predictions relation and static universality. The pion damping rate and velocity are both consistent with the dynamical critical exponent
        ζ=3/2 of Model G. Similarly, although the critical amplitude for the diffusion coefficient of the conserved
        O(4) charges are small; it is visible both in the restored phase and with finite explicit symmetry breaking, and its dynamical scaling is again consistent with
        ζ=3/2. We determine a new set of universal dynamical critical amplitude ratios relating the diffusion coefficient to a suitably defined order parameter relaxation time. We also show that in a finite volume simulation, the chiral condensate diffuses on the coset manifold in a manner consistent with dynamical scaling and with a diffusion coefficient determined by the transport coefficients of hydrodynamic pions.

        Speaker: EDUARDO GROSSI (Florence University)
      • 71
        A Realistic Coalescence Model for Deuteron Production

        Understanding the formation of (anti)nuclei in high-energy collisions has attracted large interest over the last few years. According to the coalescence model, nucleons form independently and then bind together after freeze-out if they are sufficiently close in phase-space. A recent advancement of the model is the Wigner function formalism, which allows the calculation of the coalescence probability based on the distance and relative momentum of the constituent nucleons, independently of the collision energy or system.
        The interest in explaining nuclear formation processes extends beyond standard model physics, with implications for indirect Dark Matter searches. Understanding the production mechanism of antinuclei is crucial for correctly interpreting any future measurement of antinuclear flux in space, as it would allow for the differentiation of the background originating from collisions between high-energy Cosmic Rays and the stationary Interstellar Medium.
        In this presentation, we provide a comprehensive overview of the state-of-the-art coalescence formalism, not only for deuterons but also for the more intricate case of A=3 nuclei. This represents a significant advancement, as previous efforts primarily focused on modeling the formation of simpler bounds states, e.g., deuterons. Furthermore, the model is tested for pp collision data and Heavy-Ion collisions measured at STAR. Our approach introduces a novel aspect by implementing this model into a purpose-built Monte Carlo generator called ToMCCA. This generator offers exceptional adaptability while maintaining superior performance compared to traditional general-purpose event generators.

        Speaker: Maximilian Horst (Technical University Munich)
    • Track5-UpFut: 6 talks Room Londres 1 (Palais de la Musique et des Congrès)

      Room Londres 1

      Palais de la Musique et des Congrès

      Conveners: Joachim Stroth (Goethe University Frankfurt / GSI), Joachim Stroth (Goethe University Frankfurt / GSI)
      • 72
        The NA60+ experiment at the CERN SPS

        NA60+ is a new experiment designed to study the phase diagram of the strongly interacting matter at high baryochemical potential from 200 to 550 MeV at the CERN SPS. It is focused on precision studies of thermal dimuons, heavy quark and strangeness production in Pb--Pb collisions at center of mass energies ranging from 6 to 17 GeV.

        The proposed experimental apparatus is composed of a vertex telescope located close to the target and a muon spectrometer located downstream of a hadron absorber. The vertex telescope will consist of several planes of ultra-thin, large area Monolithic Active Pixel sensors (MAPS) embedded in a dipole magnetic field. The muon spectrometer will utilize large area gaseous detectors for muon tracking and a toroidal magnet based on a new light-weight and general-purpose concept.

        An ambitious physics program is foreseen, which includes the search for chiral symmetry restoration effects through the rho-a1 mixing, the study of the order of the phase transition at large baryochemical potential through the measurement of a caloric curve, the onset of the deconfinement through the measurement of J/psi suppression. Finally the measurement of the transport properties of the medium via open charm states and the study of hadrochemistry via detection of strange hadrons and hypernuclei is also part of the physics program.

        A letter of intent was submitted at the end of 2022 and the goal is to start data taking in 2029.

        This talk will focus on the experimental apparatus, including the technical aspects and the R&D status, as well as the physics program and its competitiveness and complementarity to other experiments.

        Speaker: Dr Sabyasachi Siddhanta (INFN Cagliari, Italy)
      • 73
        The ITS3 detector and physics reach of the LS3 ALICE Upgrade.

        During LHC LS3 (2026-28) ALICE is replacing its inner-most three tracking layers by a new detector, "ITS3". It will be based on newly developed wafer-scale monolithic active pixel sensors, which are bent into truly cylindrical layers and held in place by light mechanics made from carbon foam. Unprecedented low values of material budget ($0.07\%$ per layer) and closeness to interaction point (19 mm) lead to a factor two improvement in pointing resolutions from very low $p_{\rm T}$ (O(100 MeV/$c$)), achieving, for example, 20 $\rm {\mu m}$ and 15 $\rm {\mu m}$ in the transversal and longitudinal directions, respectively, for 1 GeV/$c$ particles.
        After a successful R&D phase 2019-2023, which demonstrated the feasibility of this innovational detector, the final sensor and mechanics are being developed right now.

        This contribution will shortly review the conceptual design and the main R&D achievements, as well as the current activities and road to completion and installation. It concludes with a projection of the improved physics performance, in particular for heavy-flavour mesons and baryons, as well as for thermal dielectrons, that will come into reach with this new detector installed.

        Speaker: Chunzheng Wang (Fudan university)
      • 74
        Perspectives on (multi-strange) hypernuclei physics with the CBM experiment at FAIR

        The CBM experiment at FAIR aims to explore dense nuclear matter near the predicted quark-gluon plasma phase transition. Studying the production and decay of (multi-strange) hypernuclei in this extreme environment offers unique insights into hyperon-nucleon and hyperon-hyperon interactions, crucial for understanding the nuclear equation of state at high densities and the structure of neutron stars.
        CBM's unprecedented world-record interaction rate, combined with high-precision tracking and particle identification, enables comprehensive measurements of rare hypernuclei. This capability extends to two and three-body decays with neutral daughters, significantly expanding the accessible decay modes and providing novel constraints on theoretical models.
        Feasibility studies demonstrate CBM's ability to measure single and double hypernuclei with high precision. Sophisticated analyses of these data reveal valuable insights into hyperon-hyperon interactions. These studies pave the way for a comprehensive investigation of hypernuclei at FAIR, providing crucial data to unravel the properties of dense nuclear matter.

        Speaker: Iouri Vassiliev (GSI Helmholtzzentrum für Schwerionenforschung GmbH(GSI))
      • 75
        Physics of heavy flavors and strangeness with a time-of-flight PID upgrade at CMS in the high-luminosity LHC era

        The intriguing phenomena emerging in the high-density quantum chromodynamics (QCD) matter are being widely studied in the heavy ion program at the LHC and will be understood more deeply during the high-luminosity LHC (HL-LHC) era. The CMS experiment is under the Phase 2 upgrade towards the HL-LHC era. Among others, a new timing detector is proposed with its timing resolution for minimum ionization particles (MIP) to be 30 ps. The MIP timing detector (MTD) will also provide the particle identification (PID) ability with a large pseudorapidity acceptance covering up to $|\eta|<3$ through time-of-flight (TOF). Combining MTD with the other new subdetectors, i.e., a tracker with acceptance $|\eta|<4$ and high-granularity calorimeters with acceptance $|\eta|<5$, will enable deeper studies of high-density QCD matters in ultrarelativistic heavy ion collisions. In this presentation, the performances of a broad range of measurements in the future CMS heavy ion programs will be discussed using TOF-PID. Particular emphasis will be given to the future heavy flavor and strangeness program, including the (3+1)-dimensional evolution of heavy flavor quarks, fluctuations and transport of initially conserved quantum charges, and light nuclei physics.

        Speaker: Zhenyu Chen (Shandong University)
      • 76
        The ALICE 3 particle identification systems

        The ALICE Collaboration has proposed a completely new apparatus, ALICE 3, for the LHC Runs 5 and 6, which will enable novel studies of the quark-gluon plasma focusing on low-$p_{\rm T}$ heavy-flavour production, including beauty hadrons, multi-charm baryons and charm-charm correlations, as well as on precise multi-differential measurements of dielectron emission to probe the mechanism of chiral-symmetry restoration and the time-evolution of the QGP temperature.
        The detector consists of a large pixel-based tracking system covering eight units of pseudorapidity and including a vertex detector mounted on a retractable structure inside the beam pipe, and a comprehensive particle identification (PID) system, implementing silicon time-of-flight (TOF) detector featuring 20 ps resolution, an aerogel-based ring-imaging Cherenkov (RICH) detector, a muon identification system, and an electromagnetic calorimeter. High-purity separation of electrons with $p_{\rm T}$ as low as 60 MeV/c and up to about 3 GeV/$c$ at midrapidity, and of hadrons over a broad momentum range is achieved by the TOF and RICH, which are arranged in barrel and end-caps for full rapidity coverage.
        This contribution will present the PID subsystems conceptual design and technology options, as well as expected performance from simulation studies and first results achieved in ongoing R&D activities.

        Speaker: Giacomo Volpe (Università degli Studi di Bari &amp; INFN Sezione di Bari)
      • 77
        The silicon tracking system of the future ALICE 3 experiment at the LHC

        ALICE 3 is the next generation heavy-ion experiment proposed for the LHC Runs 5 and 6. Its tracking system will be based on a vertex detector, integrated in a retractable structure inside the beam pipe to achieve a pointing resolution of better than 10 microns for $p_{\rm T}$ > 200 MeV/$c$, and a very-large-area tracker, surrounding the vertex detector and covering 8 units of pseudorapidity (|$\eta|$ < 4). The tracking system will be based on Monolithic Active Pixel Sensor (MAPS) technology and will leverage the sensor developments carried out for the recently upgraded ALICE Inner Tracking System and for the future ALICE ITS3.

        An intensive R&D program has already started to meet the challenging detector requirements: the innermost vertex detector layer, placed at 5 mm from the interaction point, must withstand an integrated radiation load of $9\times 10^{15}$ 1 MeV neq/$\rm{cm^2}$ NIEL and 288 Mrad TID; the tracker will cover more than 50 $\rm{m^2}$ of surface, extending to a radius of 0.8 m and a total longitudinal length of about 8 m.

        This contribution will discuss the detector requirements and target sensor specifications, the ideas for mechanics and integration, and the main R&D challenges expected for the implementation of the ALICE 3 tracking system. In addition, the expected performance for novel heavy-flavour studies, ranging from D-Dbar angular and momentum correlations to the reconstruction of multicharm baryons, will be presented.

        Speaker: Pavel Larionov
    • Track7-OthTop Room Madrid (Palais de la Musique et des Congrès)

      Room Madrid

      Palais de la Musique et des Congrès

      Convener: Maria Paola Lombardo
      • 78
        Bayesian uncertainty quantification of perturbative QCD input to the neutron-star equation of state

        The equation of state of neutron-star cores can be constrained by requiring a consistent connection to the perturbative Quantum Chromodynamics (QCD) calculations at high densities. The constraining power of the QCD input depends on uncertainties from missing higher-order terms, the choice of the unphysical renormalization scale, and the reference density where QCD calculations are performed. Within a Bayesian approach, we discuss the convergence of the perturbative QCD series, quantify its uncertainties at high densities, and present a framework to systematically propagate the uncertainties down to neutron-star densities. We find that the effect of the QCD input on the neutron-star inference is insensitive to the various unphysical choices made in the uncertainty estimation.

        Ref.: Gorda, Komoltsev, Kurkela, Mazeliauskas, 2303.02175, JHEP

        Speaker: Aleksas Mazeliauskas (Institute for Theoretical Physics, Heidelberg University)
      • 79
        Strange quark nucleation in astrophysics: thermal fluctuations of the composition

        At the extreme densities reached in the core of neutron stars and related astrophysical phenomena, it is possible that quark deconfined matter takes place.
        The formation of this new phase of strongly interacting matter is likely to occur via a first-order phase transition for the typical temperatures reached in astrophysical processes (e.g. quark deconfinement could play a key role in the explosion of core-collapse supernovae from blue supergiants).
        The first seeds of quark matter would then form through a process of nucleation within the metastable hadronic phase. I will address the role of the thermal fluctuations in the hadronic composition on the nucleation of three-flavours (strange) quark matter and its implication for the phenomenology of compact stars.
        I will discuss in particular under which conditions strange quark stars
        (namely, stars entirely composed of strange quark matter) could be formed in astrophysical processes.

        Speaker: Mirco Guerrini (University of Ferrara and INFN Ferrara)
      • 80
        Implication of Quarkyonic duality to the hyperon puzzle

        Duality between quarks and baryons is one of the most fundamental properties of QCD.
        We have recently shown in Ref. [1] that the duality is closely tied to Quarkyonic nature of matter at high baryon density. We have formulated a dual model for cold, dense QCD, which allows a thermodynamic description both in terms of baryons or quarks, i.e., one can simultaneously consider the system in terms of quarks and baryons. The confinement of quarks inside baryons sets the transformation between quark and baryonic descriptions. At low density, the baryonic description is more natural, and at high density, the quark description becomes more natural, but at any density one might use one or the other. The nontrivial feature of this theory is that when we persist with the baryonic picture in the region where the quark description is more natural, the shell structure, which is the notable feature of Quarkyonic matter, appears in the pure baryonic distribution owing to the Pauli exclusions among quarks. This Quarkyonic shell structure is dual to a description in terms of quarks with a filled Fermi sea of quarks with a finite Fermi surface.

        In this talk, we discuss the implication of this Quarkyonic duality to the hyperon puzzle [2]. We extend the model to three flavors to consider the combined effect between the duality and the strangeness. We discuss that the Quarkyonic shell structure arising from the duality retains even in the presence of strangeness. As a result, the threshold density for the hyperons are shifted to even higher density compared to the conventional treatment, and the hyperonic softening of the equation of state becomes milder. This will provide a systematic way toward the resolution of the hyperon puzzle from the fundamental aspect of QCD.

        [1] Y. Fujimoto, T. Kojo, L. McLerran, To appear in Phys. Rev. Lett., arXiv:2306.04304 [nucl-th].
        [2] Y. Fujimoto, T. Kojo, L. McLerran, In preparation.

        Speaker: Yuki Fujimoto (Institute for Nuclear Theory, University of Washington)
      • 81
        Thermal dielectron measurement in Au+Au collisions with STAR BES-II data

        According to lattice Quantum Chromodynamics (QCD) prediction, there exists a phase transition from hadronic matter to Quark Gluon Plasma (QGP) at extreme high temperatures or baryon densities. Thermal dielectrons provide a unique probe to study the properties of the hot QCD medium created in relativistic heavy ion collisions. They can be emitted during the whole evolution of the medium and do not interact strongly with the medium. The invariant mass distribution of thermal dielectrons in different mass regions enables us to extract the temperature of the hot QCD medium in different phases.

        The STAR experiment collected high statistic datasets in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 7.7 - 19.6 GeV during the Beam Energy Scan program phase II (BES-II). In this talk, preliminary results of the dielectron invariant mass spectra in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 9.2 GeV will be presented and discussed in the context of other BES-II dielectron results. Furthermore, the temperature extracted from the spectra at these energies and the physics implications will also be discussed.

        Speaker: Zhen Wang
      • 82
        Thermal radiation via dielectrons with ALICE

        Electromagnetic probes such as photons and dielectrons (e$^{+}$e$^{-}$ pairs) are a unique tool to study the space-time evolution of the hot and dense matter created in ultra-relativistic heavy-ion collisions. They are produced at all stages of the collision with negligible final-state interactions. At intermediate dielectron invariant mass ($m_{\rm{ee}} > 1$ GeV/$c$), thermal radiation from the quark-gluon plasma carries information about the early temperature of the medium. At LHC energies, it is however dominated by a large background from correlated semileptonic heavy-flavor hadron decays. At smaller $m_{\rm{ee}}$, thermal radiation from the hot hadronic phase contributes to the dielectron spectrum via decays of $\rho$ mesons, whose spectral function is sensitive to chiral-symmetry restoration. Finally, at vanishing $m_{\rm{ee}}$, the real direct photon fraction can be extracted from the dielectron data. In pp collisions, such measurement in minimum bias events serves as a baseline for heavy-ion studies and a fundamental test for perturbative QCD calculations, while studies in high charged-particle multiplicity events allow one to search for thermal radiation in small colliding systems.
        In this talk, final ALICE results using the full data sample collected during the LHC Run 2 will be presented. They include measurements of the dielectron and direct-photon production in central Pb-Pb at the center-of-mass energy per nucleon pairs $\sqrt{s_{\rm NN}}$ of 5.02 TeV, as well as of direct photons in minimum bias and high-multiplicity pp collisions at 13 TeV. Finally, first results with the Run 3 pp data at 13.6 TeV, using the upgraded ALICE detector to disentangle the different dielectron sources, will be reported.

        Speaker: Jerome Jung
      • 83
        Pre-equilibrium photons from the early stages of heavy-ion collisions

        We use QCD kinetic theory to compute photon production in the chemically equilibrating Quark-Gluon Plasma created in the early stages of high-energy heavy-ion collisions. We do a detailed comparison of pre-equilibrium photon rates to the thermal photon production. We show that the photon spectrum radiated from a hydrodynamic attractor evolution satisfies a simple scaling form in terms of the specific shear viscosity and entropy density​. We confirm the analytical predictions with numerical kinetic theory simulations. We use the extracted scaling function to compute the pre-equilibrium photon contribution in central PbPb collisions. We demonstrate that our matching procedure allows for a smooth switching from pre-equilibrium kinetic to thermal hydrodynamic photon production. Finally, our publicly available implementation can be straightforwardly added to existing heavy ion models.

        Ref.: Garcia-Montero, Mazeliauskas, Plaschke, Schlichting, 2308.09747

        Speaker: Oscar Garcia-Montero (Universität Bielefeld)
    • 4:00 PM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Track1-LF Room Madrid (Palais de la Musique et des Congrès)

      Room Madrid

      Palais de la Musique et des Congrès

      Convener: Alexander Philipp Kalweit (CERN)
      • 84
        First physics measurements in Au+Au collisions from sPHENIX at RHIC

        sPHENIX, the first new detector to be built at the Relativistic Heavy-Ion Collider (RHIC) in over two decades, will bring unprecedented measurement capabilities at RHIC energies.

        sPHENIX collected its first data during the inaugural RHIC commissioning run in 2023 with Au+Au collisions. The data allow for a partial commissioning of multiple key sub-systems of the detector, including the hermetic electromagnetic and hadronic calorimetry (unique at RHIC), elements of the four-component charged-particle tracking system, and the global/forward detectors.

        This talk reports the first measurements of a number of “standard candle” properties of heavy ion collisions in commissioning data, including the charged-particle pseudorapidity density, the total transverse energy production, and the production and azimuthal modulation of neutral pions.

        The results are compared with theoretical expectations and previous measurements at RHIC, and the lessons learned for the physics data-taking in 2024 are discussed.

        Speaker: Emma McLaughlin
      • 85
        Charged-particle production in pp collisions at 13.6 TeV and Pb-Pb collisions at 5.36 TeV with ALICE

        The pseudorapidity dependence of charged particle production provides information on the partonic structure of the colliding hadrons and is, in particular at LHC energies, sensitive to non-linear QCD evolution in the initial state. For Run3, ALICE has increased its pseudorapidity coverage to track charged particles over a wider range of −3.6 < $\eta$ < 2 combining the measurement from the upgraded Inner Tracking System (ITS) and the newly installed Muon Forward Tracker (MFT).

        Particle production mechanisms are explored by addressing the charged-particle pseudorapidity densities measured in pp and Pb−Pb collisions, presenting new final results from Run 3. These studies allow us to investigate the evolution of particle production with energy and system size and to compare models based on various particle-production mechanisms and different initial conditions both at mid and forward rapidities.

        Speaker: Beomkyu Kim
      • 86
        Ultra-peripheral collisions at LHCb

        Ultra-peripheral collisions (UPCs) provide a unique environment to study pomeron- and photon-induced reactions with heavy nuclei. These interactions can produce a wide range of final state particles, from light vector mesons to heavy quarkonia, and probe potentially exotic phenomena. With a fast DAQ, full particle ID, and the ability to reconstruct very low pt particles, LHCb is uniquely well suited to studies of hadronic final states in UPC events. We will present recent LHCb results from ultra-peripheral heavy ion collisions and discuss how these impact our understanding of the partonic structure of nuclei.

        Speaker: Hengne Li
      • 87
        Production of light and strange particles as a function of the underlying event activity in small and large collision systems with ALICE

        Measurements of high-multiplicity pp and pA collisions at LHC energies have revealed that these small colliding systems exhibit quark-gluon plasma-like features, such as collective behaviour and strangeness enhancement. A method to narrow down the origin of this phenomenon is to relate the strangeness production to Multi-Parton Interactions (MPIs). Although the MPIs cannot be measured directly, the observable $R_{\rm T}$, quantifying the magnitude of the underlying event (UE), can be used as an experimental proxy.

        Final results of the charged particle production as a function of $R_{\rm T}$ in pp, p--Pb and Pb--Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV will be presented in the toward, away and transverse regions relative to the hard scattering. In addition, results on the production of identified hadrons ($\pi$, K, p) and strange particles ($\rm{K}_{S}^{0}$, $\Lambda$ and $\Xi$) as a function of $R_{\rm T}$ in pp collisions at $\sqrt{s}$ = 13 TeV will be discussed to explore the particle species dependence. All these results will be compared with predictions from QCD-inspired Monte Carlo event generators such as PYTHIA and EPOS.

        Speaker: Oliver Matonoha (CTU in Prague)
      • 88
        Light-flavour particle production as a function of transverse spherocity with ALICE

        Well established measurements of high-multiplicity proton-proton (pp) and proton-lead (p-Pb) collisions at the LHC have revealed that small collision systems show the onset of phenomena typical of heavy-ion collisions. Some of these signatures, such as strangeness enhancement and collective flow, suggest that light-flavor hadron production arises from a set of complex mechanisms whose relative contributions evolve smoothly from low to high multiplicity collisions. This implies that pp collisions cannot be seen as a simple incoherent sum of parton-parton scatterings, an idea that is common to most Monte Carlo event generators, for example, PYTHIA. Moreover, these signatures have historically been attributed to the formation of a strongly interacting medium in heavy-ion collisions. However, a formation of a medium in these smaller collision systems challanges the current theoretical frameworks.
        Studies on multi-differential strange particle production in small systems can be utilized to discriminate among the various final state effects at play and represent an important baseline for heavy-ion studies. This talk presents new results from ALICE on light-flavor particle production as a function of the transverse spherocity $(S{_{\text{O}}^{p_{\rm T}=1}})$ in pp collisions measured at $\sqrt{s}$ = 13 TeV. Utilizing narrow selections in multiplcity and $S{_{\text{O}}^{p_{\rm T}=1}}$, the observable allows for a topological selection of events that are either "isotropic" (dominated by multiple soft processes) or "jet-like" (dominated by one or few hard scatterings). The experimental results are compared with predictions from various Monte Carlo generators.

        Speaker: Adrian Nassirpour
    • Track2-HF&Q Room Rome (Palais de la Musique et des Congrès)

      Room Rome

      Palais de la Musique et des Congrès

      Convener: Prof. Zebo Tang (USTC)
      • 89
        Simulating Charm Quarks in IP-Glasma Initial Stage and Quark-Gluon Plasma: A Hybrid Approach for charm quark phenomenology

        Heavy quarks act as effective probes in relativistic heavy-ion collisions, being generated during the initial phases of the collision event. The accurate modeling of quark-gluon plasma evolution relies on a profound understanding of dynamics in the collision's early phase. We model relativistic heavy-ion collisions at LHC energy with a hybrid dynamical approach consisting of a fluctuating IP-Glasma initial state followed by viscous hydrodynamics.

        In this study, we present the first phenomenological findings on charm quark transport spanning from the IP-Glasma initial stage to the quark-gluon plasma. We employed the MARTINI event generator and PYTHIA8.1 to simulate the initial production of heavy quarks and Langevin dynamics to capture the evolution of heavy quarks in the medium. The sensitivity of heavy meson nuclear modification factor and flow coefficient to the early stage of heavy-ion collisions and bulk medium evolution is analyzed for Pb+Pb collision at 5.02 TeV. Our study provides insights into the interaction strength of charm quarks during the early phase and within the quark-gluon plasma.

        Speaker: Manu Kurian (RIKEN BNL)
      • 90
        Probing a new regime of ultra-dense gluonic matter using high-energy photons with the CMS experiment

        In ultraperipheral collisions (UPCs) involving relativistic heavy ions, the production of heavy-flavor coherent vector mesons through photon-nuclear interactions is a key focus due to its direct sensitivity to the nuclear gluon density. Experimental measurements, however, face a two-way ambiguity as each of the symmetric UPC nuclei can act as both a photon-emitter projectile and a target. This ambiguity hinders the separation of contributions from high- and low-energy photon-nucleus interactions, restricting our ability to probe the extremely small-(x) regime where nonlinear QCD effects are anticipated. The presentation will unveil the measurement of coherent heavy quarkonium photoproduction, addressing the two-way ambiguity by employing a forward neutron tagging technique in UPC PbPb collisions at 5.02 TeV. Overall these studied focus on the dominance of gluons in nuclear matter probed at higher energies.

        Speaker: Pranjal Verma
      • 91
        First measurement of heavy flavour femtoscopy using $D^0$ mesons and charged hadrons in Au+Au collisions at \hbox{${\sqrt{s_{NN}}}$ = 200~GeV} by STAR

        Heavy quarks are produced in hard partonic scatterings at the very early stage of heavy-ion collisions and experience the whole evolution of the Quark-Gluon Plasma medium. Femtoscopic correlations, i.e. two-particle correlations at low relative momentum, are sensitive to the final-state interactions and to the space-time extent of the region from which the correlated particles are emitted. A study of such correlations between the charmed mesons and identified charged hadrons could shed light on their interactions in the hadronic phase and the interaction of charm quarks with the medium.

        In this presentation, we will show the first measurement of femtoscopic correlations between $D^0$- charged hadron pairs at mid-rapidity in Au+Au collisions at ${\sqrt{s_{NN}}}$ = 200 GeV using the data taken in the years 2014 and 2016 by the STAR experiment. $D^0$ ($\bar{D^0}$) mesons are reconstructed via the $K^{-}-{\pi}^{+}$ (and its charge conjugate) decay channel using topological criteria enabled by the Heavy Flavor Tracker with excellent track pointing resolution. We will present the femtoscopic correlation function for $D^0$ transverse momentum above 1 GeV/c in the $0-80\%$ centrality. We will compare the experimental results with available theoretical models to discuss their physics implications.

        Speaker: Priyanka Roy Chowdhury
      • 92
        Examination of final-state effects in pPb collisions via measurements of the multiplicity dependence of charm hadron production with CMS

        The large masses of charm hadrons make them exceptional probes of quantum chromodynamics (QCD), providing quantitative insights into its high-density and temperature phase through their production and interaction in the nuclear medium. Charm hadron production in heavy ion collisions is influenced by several mechanisms, including energy loss, dissociation, and recombination processes. Final-state effects further modify the hadronization of heavy quarks via interactions with nearby particles (co-moving particles, quark coalescence, etc). Studying the modification of hadron production in dense environments enables the investigation of hadronization mechanisms as well as of the origin of the collectivity signals observed in the so-called small systems. We present new measurements of the production rate of charm hadrons as a function of the charged particle multiplicity in proton-lead (pPb) collisions at $\sqrt{s_{\rm{NN}}} = 8.16$ TeV. We report the first study of the prompt and nonprompt (from b-hadron decay) $\psi\rm{(2S)}$-over-$J/\psi$ cross section ratio. The results are compared with previous measurements in proton-proton (inclusive, prompt, and nonprompt) and pPb (inclusive) collisions, as well as with predictions from a comover-interaction model. In addition, measurements of the production of open charm hadrons such as $\Lambda_{c}^+$ and $D^0$ will be presented.

        Speaker: Austin Alan Baty
      • 93
        Study of charm quark and QGP medium interactions via $\Lambda_\text{c}^+$ and $\text{D}^{0}$ production and collective flow in the CMS

        Since charm quarks are massive, they are dominantly produced in the early stage of a collision. In heavy ion collisions, they propagate through the quark-gluon plasma (QGP) and provide important information about the initial stages of the collision, and the properties of the QGP medium. The interaction between heavy quarks and the QGP affects the hadronization of heavy quarks and their azimuthal distribution and transverse momentum ($p_\text{T}$) spectrum. By comparing the $\Lambda_\text{c}^+$ baryon and $\text{D}^0$ meson productions, and measuring the azimuthal anisotropy of the $\text{D}^0$ meson, we can study the charm quark hadronization and the interaction between charm quark and the QGP medium. In this talk, we present the measurements of $\Lambda_\text{c}^+$ baryon production, the $\Lambda_\text{c}^+/\text{D}^0$ yield ratio at $\sqrt{s_\text{NN}}=5.02$ TeV in proton-proton collisions and different centrality regions of lead-lead (PbPb) collisions. The results indicate that the production of $\Lambda_\text{c}^+$ baryons is suppressed for more central events in PbPb, and the coalescence does not play a significant role in the hadronization of $\Lambda_\text{c}^+$ baryon at $p_\text{T}>10$~GeV. Furthermore, we present the measurements of the azimuthal anisotropy coefficients ($v_2$ and $v_3$), and $R_\text{AA}$ of prompt $\text{D}^0$ in PbPb collisions as a function of $p_\text{T}$ from central to mid-central collisions. Clear centrality dependencies of prompt $\text{D}^0$ meson $v_2$ and $R_\text{AA}$ are observed. No evidence of the effect of the Coulomb field on the collective flow of charm hadron is found.

        Speaker: Soumik Chandra
    • Track4-Bulk&Phase: 5 talks Room Bruxelles (Palais de la Musique et des Congrès)

      Room Bruxelles

      Palais de la Musique et des Congrès

      Convener: Mesut ARSLANDOK (Yale)
      • 94
        Collision Energy Dependence of Hypertriton Production in Au+Au Collisions at RHIC

        Despite extensive measurements on the production yields of light nuclei in heavy-ion collisions, a consensus on their formation mechanism remains elusive. In contrast to normal nuclei, hypernuclei carries strangeness and can offer an additional dimension for such studies. In particular, the hypertriton $^{3}_{\Lambda}\rm{H}$, a bound state consisting of a proton, neutron and $\Lambda$ hyperon, is the lightest known hypernucleus with a very small binding energy of $\sim$130 keV. Currently, published measurements of the $^{3}_{\Lambda}\rm{H}$ yield are scarce and are limited to very low ($\sqrt{s_{NN}} < 5$ GeV) or very high collision energies ($\geq 200$ GeV). Precise measurements on the energy dependence of $^{3}_{\Lambda}\rm{H}$ production will give invaluable information on hypernuclei production mechanisms due to its unique intrinsic properties.

        In this presentation, we will present comprehensive measurements of the collision energy dependence of $^{3}_{\Lambda}\rm{H}$ transverse momentum $p_T$ and $p_T$-integrated yield at mid-rapidity in Au$+$Au collisions at ten collision energies between $3$ and $27$ GeV. It is found that thermal model calculations under-predict the $^{3}_{\Lambda}\rm{H}$ yield and the $^{3}_{\Lambda}\rm{H}/\Lambda$ ratio by a factor of $\sim$2 in the reported energy region, while coalescence calculations are closer to data. We will also present the mean $p_T$ of $^{3}_{\Lambda}\rm{H}$ as a function of collision energy. The mean $p_T$ of $^{3}_{\Lambda}\rm{H}$ is observed to be lower than the Blast-Wave expectation using the same freeze-out parameters from light hadrons. These observations suggest that similar to light nuclei, hypertritons are formed at a later stage than light hadrons possibly through nucleon/hyperon coalescence during these collisions.

        Speaker: Xiujun Li
      • 95
        Studying (anti)nucleosynthesis via event-by-event fluctuations at the LHC with ALICE

        The production of light (anti)nuclei in heavy-ion collisions has been extensively studied both experimentally and theoretically. Different phenomenological descriptions of (anti)nucleosynthesis differ in the predicted rapidity range over which the conservation of baryon number is realized. Recent studies of the event-by-event Pearson correlation between the antideuteron and antiproton numbers suggest that the baryon number is conserved over a smaller rapidity range than that observed for ordinary hadrons. These observations can be explained by invoking nuclear coalescence mechanisms, which require small rapidity gaps between the nucleons merging into nuclei. In this contribution, the most recent results obtained by the ALICE Collaboration from the study of antideuteron–antiproton and antideuteron–Λ correlations in Pb–Pb collisions are reported. The antideuteron–antiproton correlation provides a benchmark for (anti)nucleosynthesis models, while the antideuteron–Λ correlation arises from baryon-number conservation in the processes underlying the formation of (anti)nuclei since antideuterons do not contain Λ-baryons, providing a crucial complementary test of the coalescence hypothesis. The presented comparison between experimental results and an extensive array of phenomenological models provides new insights into (anti)nucleosynthesis mechanisms.

        Speaker: Mario Ciacco
      • 96
        Study of baryon-strangeness and charge-strangeness correlations in Pb--Pb collisions at 5.02 TeV with ALICE

        In the quest to unravel the mysteries of the strong force and the underlying properties of the quark-gluon plasma, the ALICE collaboration at CERN has carried out a comprehensive study focusing on the correlations between net-conserved quantities such as net-baryon, net-charge and net-strangeness. These correlations play a crucial role in the study of QCD phase structure as they are closely related to the ratios of thermodynamic susceptibilities in lattice QCD (LQCD) calculations. Recent LQCD results also suggest a significant influence of the magnetic field on the susceptibility ratios, paving the way for the use of net-conserved charges to study the magnetic field produced in peripheral heavy-ion collisions.
        This presentation introduces new results focusing on the first-order correlations between net-kaon and net-proton as well as net-kaon and net-charge. Here, the net-proton and net-kaon serve as proxies for the net-baryon and net-strangeness, respectively, and measurements are performed as a function of centrality in Pb--Pb collisions at 5.02 TeV using data recorded by the ALICE detector. A comparative analysis is presented, drawing connections with corresponding results at lower collision energies from the STAR experiment at RHIC. Theoretical predictions from the hadron resonance gas model, HIJING and EPOS event generators are also compared with experimental results, providing insights into the effects of resonance decays and charge conservation laws. This comprehensive study attempts to bridge experimental data to LQCD calculations and contribute to our understanding of the complex dynamics inherent in high-energy nuclear collisions.

        Speaker: Swati Saha
      • 97
        Measurements of Kaon Femtoscopy in Au+Au Collisions at $\sqrt{s_{NN}}$ = 3.0 - 4.5 GeV by the STAR experiment

        Two-particle correlations are used to extract the space-time and dynamical information of the particle-emitting source created in heavy-ion collisions. The source radii extracted from them characterize the system at the kinetic freeze-out, i.e., the last stage of particle interactions. Kaons can provide a more direct view of the particle-emitting source than pions as they have smaller hadronic cross section and less contribution from long lifetime resonances. It is particularly interesting to study the energy dependence of the extracted kaon source parameters.

        In this talk, the measurements of neutral $\rm K_{s}^{0}-K_{s}^{0}$ and charged $\rm K^{+}-K^{+}$ correlation functions from Au+Au fixed-target collisions at $\sqrt{s_{\rm NN}}$ = 3.0, 3.2, 3.5, 3.9 and 4.5 GeV, measured by the STAR experiment, will be presented. This is the first such systematic measurement of correlation functions involving strangeness in the high baryon region. These new results will be compared with those from pion femtoscopic measurements and will be discussed with the calculations from hadronic transport model.

        Speaker: Bijun Fan (CCNU)
      • 98
        Measurement of strange particle femtoscopic correlations at the CMS experiment

        Particle correlations have been traditionally employed in the study of the collective phenomena observed in hadronic and heavy ion collisions by using azimuthal distributions, while quantum statistical effects and final-state interactions can be accessed by femtoscopic measurements. Femtoscopic correlations of identified hadrons are measured with data recorded by the CMS experiment at the LHC over a broad multiplicity range and different pair transverse momenta. In this talk, results on the femtoscopic correlations of strange particles ($\text{K}^{0}_{\text{S}}$, $\Lambda$ and $\bar{\Lambda}$) are reported for proton-lead (pPb) collisions at $\sqrt{s_{\mathrm{NN}}} = $ 8.16 TeV and lead-lead (PbPb) collisions at $\sqrt{s_{\mathrm{NN}}} = $ 5.02 TeV using LHC Run 2 data collected by the CMS experiment. The strong interaction scattering parameters, scattering length and effective range, are extracted using the Lednick\'y-Lyuboshitz model for both pPb and PbPb collisions, and compared with other experimental and theoretical results. The measurements are performed in several multiplicity and centrality bins and as a function of of the pair average momentum.

        Speaker: Raghunath Pradhan
    • Track5-UpFut: 2 talks Room Londres 1 (Palais de la Musique et des Congrès)

      Room Londres 1

      Palais de la Musique et des Congrès

      Convener: Dr Nu Xu (LBNL)
      • 99
        Intelligent experiments through real-time AI: Fast Data Processing and Autonomous Detector Control for sPHENIX and future EIC detectors

        This new DOE FOA project, first funded by the DOE Office of Science Nuclear Physics AI-Machine Learning initiative in 2022, focuses on leveraging cutting-edge AI technology to address the data processing challenges posed by high-energy nuclear experiments, such as those at RHIC, LHC, and the future EIC. We first aim to develop a demonstrator to process high-rate data streams from sPHENIX experiment tracking detectors in real-time to identify rare heavy flavor events in p+p collisions. Our approach integrates real-time readouts and an intelligent control system, accelerating AI inference with FPGA hardware. This enables the efficient collection of rare heavy-flavor events in high-rate p+p collisions (~1MHz), optimizing the use of limited DAQ bandwidth (~15kHz). The project employs Graph Neural Network-trigger algorithms, trained with sPHENIX p+p collision simulation data, and leverages the hls4ml package for AI model conversion into Firmware. Real-time AI technologies are deployed on powerful FELIX-712 boards with Xilinx Kintex Ultrascale FPGA. Successful deployment of a demonstrator at sPHENIX promises immediate benefits, minimizing computation resources, and accelerating the end-to-end pipeline from experiments to physics discovery, in particular, heavy-flavor measurements in p+p and possibly p+Au collisions. The approach is transferable to other fields requiring high-throughput data streams and real-time detector control, including future EIC experiments. For the EIC, we are developing a DIS-electron tagger using AI-ML algorithms for real-time identification of DIS electrons and characterization of global kinematics. In this talk, we highlight the latest progress in AI-intelligent heavy-flavor triggering for sPHENIX and DIS electron tagger algorithm development for EIC, demonstrating the transformative potential of AI and FPGA technologies in high-energy nuclear and particle experiments' real-time data processing pipelines.

        Speaker: Marzia Rosati (Iowa State University)
      • 100
        Fast timing silicon R$\&$D for the future Electron-Ion Collider

        The proposed Electron-Ion Collider (EIC) will utilize high-luminosity high-energy electron+proton ($e+p$) and electron+nucleus ($e+A$) collisions to solve several fundamental questions including searching for gluon saturation and studying the proton/nuclear structure. High granularity and low material budget silicon vertex and tracking detector with fine spatial resolution is essential to perform a series of high precise measurements at the EIC. Complementary to the ongoing EIC project detector technical design carried out by the ePIC collaboration, several new detector R$\&$D, which aims for the ePIC detector upgrade or the EIC detector II development, has started with the support of the EIC generic R$\&$D project. A Depleted Monolithic Active Pixel Sensor (MALTA2) based fast timing silicon tracking detector has been proposed to provide additional hits for track reconstruction in the far-forward and far-backward region at the EIC to improve the overall track reconstruction quality. The fast timing resolution of the MALTA2 technology will help reject background events at the EIC as well. We will present the detector design of the proposed MALTA2 based far forward/backward tracking detector supported by the EIC generic R$\&$D program, progress of the MALTA2 R$\&$D from bench tests and scheduled beam test at CERN and the development of a new MALTA2 stave design with reduced material budgets. The evaluated impacts on the EIC $e+A$ physics will be present as well.

        Speaker: Xuan Li (Los Alamos National Laboratory)
    • Track7-OthTop: 3 talks Room Londres 1 (Palais de la Musique et des Congrès)

      Room Londres 1

      Palais de la Musique et des Congrès

      Convener: Dr Nu Xu (LBNL)
      • 101
        Searching for the baryon number carrier with heavy-ion collisions at the STAR experiment

        Baryon number is a strictly conserved quantum number, which holds the universe as we know it today. In the quark model, each quark is assigned one third of the baryon number. However, string junctions, non-perturbative Y-shaped topology of gluon fields connected to three quarks, are expected to emerge in dynamical processes and have been proposed as an alternative carrier of the baryon number. Neither of these scenarios have been verified experimentally though. In this contribution, three independent measurements, utilizing heavy-ion collisions recorded by the STAR experiment at RHIC, will be presented, in search for the baryon number carrier. Firstly, the charge and baryon number transport over a large rapidity gap are measured in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\rm{NN}}}$ = 200 GeV. The results show significantly more baryon transport than charge transport from beam to midrapidity. The second measurement selects $\gamma$+Au collisions from Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 54 GeV. The slope of the baryon number transport distribution against rapidity in $\gamma$+Au collisions is found to be smaller than those predicted by PYTHIA and HERWIG event generators, which assign baryon number to valence quarks. Thirdly, the slope measurement is extended to hadronic Au+Au collisions with collision energies ranging between 7.7 and 200 GeV. The rapidity slope of the baryon number transport is found to be independent of centrality and also smaller than event generators. All three measurements are incompatible with the scenario of valence quarks carrying the baryon number.

        Speaker: Rongrong Ma
      • 102
        Shedding light on strong interactions in three-baryon systems with ALICE Run 3 data

        The interactions of Λ hyperons with nucleons are of high interest for the studies of the composition of the inner core of neutron stars. Their equation of state requires a precise knowledge of the two- and three-body interactions at small distances which are not yet well constrained by the existing experimental data. ALICE has introduced a novel approach to investigate such interactions by measuring femtoscopic correlation functions of particles emitted with distances of around 1 fm in high-energy pp collisions. This method allows the study of various hadron-nucleus pairs and, for the first time, direct access to the 3->3 free scattering process.

        In this talk, ALICE measurements of p-d, p-p-p and p-p-Λ correlation functions are presented in pp collisions at √s = 13.6 TeV, with a sevenfold increase in the statistical sample compared to Run 2. Moreover, the first-ever measurement of Λ-d pairs in pp collisions will be presented. The measured correlation functions will be compared to theoretical predictions showing sensitivity to the three-body dynamics.

        Speaker: Laura Serksnyte (TUM)
      • 103
        Directed Flow of $\Lambda$, $^{3}_{\Lambda}{\rm H}$, and $^{4}_{\Lambda}{\rm H}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 3.2, 3.5, 3.9 and 4.5 GeV at RHIC

        Studying hyper-nuclei production and their collectivity can shed light on their production mechanism as well as the hyperon-nucleon interactions. Heavy-ion collisions from the RHIC beam energy scan phase II (BES-II) provide an unique opportunity to understand these at high baryon densities.

        In this presentation, we will show a systematic study on energy dependence of the directed flow for $\Lambda$ and hyper-nuclei ($^{3}_{\Lambda}{\rm H}$, $^{4}_{\Lambda}{\rm H}$) from mid-central Au+Au collisions at $\sqrt{s_{NN}}$ = 3.2, 3.5, 3.9 and 4.5 GeV, collected by the STAR experiment with the fixed-target mode during BES-II. The rapidity (y) dependence of the hyper-nuclei $v_{1}$ is studied in mid-central collisions. The extracted $v_{1}$ slopes ($dv_{1}/dy|_{y=0}$) of the hyper-nuclei are positive and decrease gradually as the collision energy increases. These hyper-nuclei results will be compared to that of light-nuclei including p, d, t/$\rm ^{3}He$ and $\rm ^{4}He$. Finally, discussions will be made using comparison to hadronic transport model including coalescence after-burner calculations.

        Speaker: Junyi Han
    • Posters Hall Schweitzer, ground floor (PMC)

      Hall Schweitzer, ground floor


    • Track1-LF: 5 talks Room Madrid (Palais de la Musique et des Congrès)

      Room Madrid

      Palais de la Musique et des Congrès

      Convener: Rene Bellwied (University of Houston)
      • 104
        Novel constraints for the multi-strange meson-baryon interaction using correlation measurements with ALICE

        This talk presents unprecedented correlation measurements involving Λ, Ξ, kaons and pions obtained by ALICE in pp collisions at $\sqrt{s}$ = 13 TeV. Several measurements are presented for the first time, constituting new experimental constraints on the S = −1, −2 meson-baryon interactions and the nature of exotic states. The strong interactions involving mesons and baryons with strangeness content deliver a rather broad spectrum of interesting states, arising from the rich interplay between the elastic and inelastic QCD dynamics. The Λ(1405) in the S = −1 sector is an example of such molecular state, but in order to build a solid description of its inner structure more data are needed, particularly below the K ̄ N energy threshold. Much less experimental data are currently available on another potential molecular state, the Ξ(1620), predicted and observed in the S = −2 meson-baryon sector. The presented correlation data put new constraints on these sectors and deliver a better understanding on such states.

        Speaker: Valentina Mantovani Sarti
      • 105
        p-$\phi$ femtoscopic correlation analysis using a dynamical model

        Femtoscopic analysis using a two-particle correlation function has attracted significant interest as a method to study hadron interactions. According to the Koonin-Pratt formula [1, 2], the correlation function is interpreted as a convolution of the source function, which reflects the dynamics of the nuclear collisions, and the square of the relative wave function, which reflects the quantum statistical effect and the final state interaction between the pair of interest.

        Recently, the ALICE collaboration measured the p-$\phi$ correlation function [3] in high-multiplicity p+p collisions, revealing a spin-averaged attractive interaction. In Ref. [4], the correlation function was analyzed on a spin channel-by-channel basis using the Gaussian source function. By adopting the lattice QCD potential for the $^4S_{3/2}$ channel [5], the strong attractive potential accommodating a bound state in the $^2S_{1/2}$ channel was extracted from the comparison with the experimental correlation function.

        In this study, we analyze the p-$\phi$ correlation function in high-multiplicity p+p collisions at $\sqrt{s}=13~\text{TeV}$ using the source function from a state-of-the-art hydrodynamics-based model, DCCI2 [6], which can describe the entire process of collision reactions. We find a non-Gaussian long tail in the source function due to hadronic rescattering, leading to deviations in the resulting correlation function compared to that using the Gaussian source function. In addition, we reveal that the correlation function exhibits an intriguing behavior in the small relative momentum regions due to the collectivity of the generated matter. These results emphasize the importance of employing the source function that accurately reflects the collision dynamics for future high-precision studies of hadron interactions via femtoscopy. Finally, from the comparison with the experimental correlation function, we find that the present femtoscopic analysis using the DCCI2 source function also suggests the existence of a p-$\phi$ bound state in the $^2S_{1/2}$ channel, as in the case using the Gaussian source function.

        [1] S. E. Koonin, Phys. Lett. B 70, 43 (1977).
        [2] S. Pratt, Phys. Rev. D 33, 1314 (1986).
        [3] ALICE Collaboration, Phys. Rev. Lett. 127, 172301 (2021).
        [4] E. Chizzali et al., Phys. Lett. B 848, 138358 (2023).
        [5] Y. Lyu et al., Phys. Rev. D 106, 074507 (2022).
        [6] Y. Kanakubo, Y. Tachibana, and T. Hirano, Phys. Rev. C 105, 024905 (2022).

        Speaker: Kenshi Kuroki (Sophia University)
      • 106
        Measurement of Proton-$\Xi^{-}$ Correlation Function in Isobar Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV with the STAR Detector

        Femtoscopy is a powerful technique used to investigate the emission source and interaction potential between pairs of particles. The two-particle correlation function, which reveals valuable information about the space-time evolution of the emitting source and final state interaction, is the primary observable of interest. A detailed knowledge of hyperon-nucleon (Y-N) interaction is important for understanding the equation of state of neutron star. In high energy heavy-ion collisions, a large number of particles including hyperons are produced, which offers a great opportunity to study those interactions via femtoscopic measurements.

        In this talk, we present the measurements of p-$\Xi^{-}$ correlations with high statistics in Isobar collisions (Ru+Ru, Zr+Zr) at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV by the STAR experiment. By employing Lednicky-Lyuboshitz approach, the scattering length ($f_{0}$) and effective range ($d_{0}$) of proton and $\Xi^{-}$ interactions are extracted. Results from Au+Au collisions at the same energy will be used for comparison. In addition, these parameters will be compared to those from Lattice QCD calculations.

        Speaker: Boyang Fu (CCNU)
      • 107
        Differential measurement of the common particle emitting source using p–p and p–Λ correlations in pp collisions at 13.6 TeV with ALICE

        Using data collected in high-multiplicity pp collisions at 13 TeV with the ALICE detector during the Run 2 period of the LHC, the femtoscopy technique has been successfully employed to extend the boundaries of known hadron-hadron interactions to the S=-3 sector and to initiate studies of charmed and three-body systems. The key element of these analyzes is the precise modeling of the common particle-emitting source, whose size was found to scale with the average transverse mass $m_{\rm T}$ of the studied particle pair. During the ongoing Run 3 data-taking period, the ALICE experiment collected the largest minimum bias dataset in its history, consisting of about 500 billion events at 13.6 TeV. This provides for the first time the opportunity to additionally investigate the common source as a function of event multiplicity.
        In this contribution, the measurement of the size of the common particle-emitting source from p–p and p–Λ pair correlations as a function of event multiplicity and $m_{\rm T}$ of the particle pairs are presented. This is achieved by modeling the final-state interaction of p–p pairs with realistic potentials anchored to scattering data, whereas the p–Λ interaction is modeled using state-of-the-art EFT calculations. The presented results will be the basis for all further femtoscopic studies with ALICE in Run 3.

        Speaker: Anton Riedel (Technical University of Munich)
      • 108
        Measurement of strange baryon production in charged-particle jets in pp and p-Pb collisions with ALICE

        Collective effects similar to those in Pb-Pb collisions have been observed in smaller systems, such as pp and p-Pb collisions. Among these is the increase of the strange to non-strange hadron ratio with charged-particle multiplicity density. Understanding these effects requires a detailed description of the production mechanisms of strange hadrons, which is obscured by large uncertainties in the gluon-initiated particle shower and hadronisation models. Much of our knowledge of particle showers is based on results from 𝑒+𝑒− collisions, which is sensitive to quark-initated fragmentation patterns, but leaves gluon fragmentation poorly constrained. By studying the production of strange hadrons in hadronic collisions, which are rich in gluon-initiated final states, we can probe these mechanisms and, using data from p-Pb collisions, we can disentangle the contributions in jets from those of the bulk.
        In this talk, we present published results on the production of K$^0_{\rm S}$, Λ($\bar{\rm{\Lambda}}$), Ξ± and Ω± hadrons in charged-particle jets and the underlying event in pp and p-Pb collisions with ALICE.
        In addition, we show a novel measurement of jet fragmentation into Λ and K$^0_{\rm S}$ hadrons in pp collisions at $\sqrt{s}$=13.6 TeV with ALICE.

        Speaker: Gijs van Weelden (Nikhef)
    • Track2-HF&Q: 5 talks Room Rome (Palais de la Musique et des Congrès)

      Room Rome

      Palais de la Musique et des Congrès

      Conveners: Rachid GUERNANE (LPSC CNRS/IN2P3), Rachid Guernane (LPSC Grenoble)
      • 109
        Measurement of $\rm D^{0}$ Meson Tagged Jets in Au+Au Collisions at $\sqrt{s_{\rm NN}} = 200$ GeV

        The Quark-Gluon Plasma (QGP) produced in heavy-ion collisions can be studied using hard probes, such as $D^0$-meson tagged jets created at the initial collision stage. The jet yield, shape, and its sub-structure get modified due to interactions with the medium compared with its vacuum propagation. This phenomenon is known as jet quenching.

        The transverse momentum ($p_{\text{T}}$) fraction of the jet, carried by hadrons along the jet axis ($z = \vec{p}_{\text{T},\text{hadron}} \cdot \vec{p}_{\text{T},\text{jet}}/|p_{\text{T},\text{jet}}|^2$), is related to jet fragmentation. The generalized angularities $\lambda_{\alpha}^{\kappa}$ characterize the jet substructure and they can distinguish jets initiated by light and heavy quarks, and gluons where the different choice of $\kappa$ and $\alpha$ parameters tunes the sensitivity of the observable to various jet aspects. Measurements of the nuclear modification factor $R_{\text{CP}}$ of $D^0$ jets as a function of the transverse momentum fraction $z$ and the generalized angularities in heavy-ion collisions open ways to investigate modifications of heavy quark fragmentation function and jet substructure in the QGP. In addition, studying radial distribution of $D^0$ mesons in jets allows one to investigate the charm quark diffusion in the medium.

        In this contribution, we report the measurement of $D^0$ meson tagged jets in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200$ GeV by the STAR experiment at RHIC. We present $R_{\text{CP}}$ as a function of $p_{\text{T},\text{jet}}$ and $z$, measurements of generalized angularities, and the radial profile of the $D^0$ mesons for $D^0$ jets. These results may help distinguish between various models describing jet quenching and heavy flavor quark in-medium energy loss.

        Speaker: Ondrej Lomicky
      • 110
        Study of charm fragmentation with charm meson and baryon angular correlation measurements with ALICE

        Fragmentation functions, which describe the fraction of the heavy-quark momentum carried by the heavy-flavour hadron, are one of the key components of the factorisation theorem used to calculate heavy-flavour hadron production cross-sections. Such functions are typically parametrised exploiting measurements performed in $\mathrm{e^+e^-}$ and $\mathrm{e^-p}$ collisions, under the assumption of fragmentation as a universal hadronisation mechanism across leptonic and hadronic collision systems. However, measurements of charm-hadron spectra and of the ratios of charmed-hadron abundances in pp collisions at LHC have proved that the fragmentation of heavy quarks into the different hadron species differ in hadornic and leptonic collisions.

        In this talk, we present measurements of differential observables that consider the surrounding hadronic population in addition to the heavy-flavour hadron itself. These measurements allow for a closer connection to the charm fragmentation functions and put stronger constraints on the properties of hadronisation in hadronic collisions.

        In particular, we report the results of angular correlations between D mesons and charged particles in pp collisions, including the first studies with Run 3 data. We will also show the comparison between charm meson angular correlations with charged particles and charm baryon ($\Lambda_{c}^{+}$) correlations in pp collisions. Such measurement will give insights on the differences of the charm fragmentation between charm baryons and mesons. We also present the final measurement of the fraction of longitudinal momentum of jets carried by $\Lambda_{c}^{+}$ baryons in pp collisions at $\sqrt{s} = 13$ TeV.

        Speaker: Antonio Palasciano
      • 111
        $R_{AA}$ and $v_n$: relativistic transport approach for charm and bottom toward a more solid phenomenological determination of $D_s(T)$

        Quasi-Particle Model (QPM) allows for a good description of the main features of lattice QCD (lQCD) thermodynamics and for charm quark supplies a satisfying description of $R_{AA}(p_T)$ and $v_2(p_T)$ of D mesons[1,2]. Within an event-by-event full Boltzmann transport approach followed by a hybrid hadronization via coalescence plus fragmentation, we investigate the extension to bottom quark dynamics discussing predictions for $R_{AA}(p_T)$ and $v_{2,3}(p_T)$ of B mesons comparing to the available experimental data by ALICE collaboration on electrons from B meson decay [3]. A sizeable $v_{2,3}$ is found with important implications on bottomonium $\Upsilon$ production. Furthermore, the extension to bottom quark allows to investigate the mass dependence of $D_s(T)$ towards the infinite mass limit assumed in lQCD calculations. We find a significant breaking of the scaling of thermalization time $\tau_{th}$ with $M_Q/T$, entailing a $D_s$ for $M\rightarrow \infty$ in agreement with the recent lQCD data with dynamical quarks. Furthermore, we extend our QPM approach to a more realistic model in which partonic propagators explicitly depend on quark momentum (QPMp) following Dyson-Schwinger studies [4]. The QPMp improves the description of lQCD quark susceptibilities, understimated in the standard QPM approach and entails a $D_s$ with a stronger non-perturbative behaviour near to $T_c$ which leads to a better agreement with the recent lQCD data.The implication of QPMp extensions on the $R_{AA}(p_T)$ and $v_n (p_T)$ is under study and hints at a lowering of the global $\chi^2$ toward a more solid extrapolation of $D_s(T)$.

        [1] M. L. Sambataro, S. Plumari and V. Greco, Eur. Phys. J. C 80 (2020) no.12, 1140.
        [2] M.L.Sambataro, Y, Sun, V. Minissale, S.Plumari and V.Greco, Eur.Phys.J.C 82 (2022) 9, 833 .
        [3] M.L.Sambataro, V. Minissale, S. Plumari and V. Greco, Phys.Lett.B 849 (2024) 138480.
        [4] M.L.Sambataro et al., in preparation.

        Speaker: Maria Lucia Sambataro (Università degli Studi di Catania-INFN(LNS))
      • 112
        Forward rapidity elliptic flow measurements in PHENIX Au+Au collisions at 200 GeV

        Measurements of elliptic flow ($v_2$) of light and heavy flavor particles can provide key insight into the transport properties and collective behavior of the Quark Gluon Plasma (QGP). The PHENIX experiment at RHIC has a unique coverage at forward rapidity ($1.2\leq|\eta|\leq2.2$), and large muon datasets collected during the 2014 and 2016 runs, allowing for statistically significant heavy flavor $v_2$ measurements in this region at RHIC energies. For $J/\psi$ in this region, smaller charm quark yields are observed hinting that charm quark coalescence, a potential dominating source of $J/\psi$ $v_2$, may not play a significant role given that the majority of $c\bar{c}$ pairs are produced at mid-rapidity in central collisions. In the forward rapidity region, the $v_2$ of light hadrons and muons from heavy flavor decays are also measured and the results are compared to measurements at mid-rapidity. Measurements at forward rapidity sample different initial and final state effects and therefore the produced particles may be subject to different pressure gradients. We present final results of $J/\psi$, open heavy flavor, and charged hadron $v_2$ measured using the PHENIX muon arms and using the combined high statistic 2014 and 2016 Au+Au datasets. This combination of elliptic flow measurements between various particle species will be the first comprehensive look at heavy flavor dynamics in forward rapidity at RHIC.

        Speaker: Luis Bichon III (Vanderbilt University)
    • Track3-Res&Hyp: 5 talks Room Londres 1 (Palais de la Musique et des Congrès)

      Room Londres 1

      Palais de la Musique et des Congrès

      Convener: Benjamin Doenigus (Goethe-University Frankfurt)
      • 113
        Antihelium identification and antihypertriton observation with LHCb

        The production of helium and anti-helium nuclei is studied for the first time with the LHCb detector in pp collisions at $\sqrt{s} = 13 \, TeV$. The used dataset was collected between the years 2016 to 2018 and corresponds to an integrated luminosity of $L = 5.5 fb^{-1}$. The helium nuclei are identified using ionization losses in the silicon sensors of the VELO and ST detectors, alongside timing measurements in the OT drift tubes. A total of $10^5$ prompt helium and anti-helium are identified with negligible background contamination. First application of this method is the reconstruction of hypertritons via the 2-body decay into Helium-3 and a charged pion. A total of $10^2$ hypertriton candidates are found. This example proves the feasibility of a rich program of measurements of QCD and astrophysics interest involving light nuclei.

        Speaker: Gediminas Sarpis (University of Edinburgh)
      • 114
        Investigating the system size dependence of hypernuclei production with A < 5 using the ALICE detector

        The production of (anti)hypernuclei is among the most promising probes for studying the production mechanism of light nuclei in high-energy hadronic collisions. According to coalescence, the production of $\mathrm{^{3}_{\Lambda} H}$, $\mathrm{^{4}_{\Lambda} H}$, and $\mathrm{^{4}_{\Lambda} He}$ in small colliding systems (pp and p-Pb) is extremely sensitive to their internal wave function, while in the Statistical Hadronisation Models (SHMs) the nuclear structure does not enter explicitly in the prediction of the yields.
        In this contribution, the production measurements of $\mathrm{^{3}_{\Lambda} H}$, $\mathrm{^{4}_{\Lambda} H}$, and $\mathrm{^{4}_{\Lambda} He}$ from pp to the most central Pb--Pb collisions are presented. The results are based on the data samples collected by ALICE during the LHC Run 2 and Run 3. For the $\mathrm{^{3}_{\Lambda} H}$, in addition, an innovative method to extract its properties starting from the system size dependency of its production yield will also be presented.

        Speaker: Yuanzhe Wang
      • 115
        Measurements of $^{4}_{\Lambda}$H and $^{4}_{\Lambda}$He production in $\sqrt{s_{\rm NN}}$ = 3.0 - 3.9 GeV Au+Au collisions from STAR

        Hypernuclei, which are bound states of nuclei with at least one hyperon, serve as excellent experimental probes for studying the hyperon-nucleon ($Y$-$N$) interaction.
        The A=4 mirror hypernuclei ($^{4}_{\Lambda}$H(0$^+$) and $^{4}_{\Lambda}$He(0$^+$)) is substantially tighter bound compared to the hypertriton ($^{3}_{\Lambda}$H). The existence of the spin-1 excited states ($^{4}_{\Lambda}$H$^{*}$(1$^+$) and $^{4}_{\Lambda}$He$^{*}$(1$^+$)) may also enhance the measured yields through feed-down. As such, their yields allow us to gain insight on the effects of hypernuclear binding, spin and isospin content on their production in heavy-ion collisions.

        In this talk, we will present the first measurements of A=4 hypernuclei ($^{4}_{\Lambda}$H and $^{4}_{\Lambda}$He) production from the RHIC-STAR experiment utilizing the fixed target datasets.
        The transverse momentum $p_{\rm T}$ spectra and yields $dN/dy$ as a function of rapidity will be shown from $\sqrt{s_{\rm NN}}$ = 3.0, 3.2, 3.5 and 3.9 GeV Au+Au collisions.
        The $dN/dy$ and $$ of $^{4}_{\Lambda}$H and $^{4}_{\Lambda}$He will be compared between the aforementioned energies to investigate their energy dependencies. The rapidity and energy dependencies of the ratio of $^{4}_{\Lambda}$H to $^{4}_{\Lambda}$He will also be shown to investigate the isospin dependence.
        Furthermore, calculations from thermal model and transport model (JAM) plus coalescence afterburner will be compared to these results and the relevant physics implications will be discussed.

        Speaker: Chenlu Hu
      • 116
        Investigating the hidden strangeness content of exotic resonance with ALICE

        The investigation of the quark content of hadrons has been a major focus of nonperturbative strong interaction models. The basic quark model describes baryons as composed of three quarks/antiquarks and mesons as a quark-antiquark pair. However, in the last decade, several resonances have been observed in the mass range 900-2000 MeV/$c^{2}$ (e.g. $f_{0}$(980) and $f_{1}$(1285)) that could have exotic quark compositions. Theory predicts it can be a linear composition of two u and d quarks or can have hidden strangeness to form tetra-quark hadrons or hadrons with hybrid structure.
        The excellent particle identification capabilities of the ALICE detector along with the large data sample collected in pp and p--Pb collisions provide an opportunity to explore the high mass resonances. This study reports the first measurement of production cross section of $f_{1}$ and $f_{0}$ resonances in pp and p--Pb collisions at the LHC energies. The measurements of yields will be presented and will be compared to the statistical hadronization model (SHM) to shed light on the hidden strange content of these resonances. In addition to that, a multiplicity dependent study of $f_{0}$ resonances will be presented to search for the possible rescattering effect in the hadronic phase of high multiplicity pp and p-Pb collisions.

        Speaker: Prottay Das
      • 117
        Energy dependence of ϕ(1020) meson production in nucleus-nucleus collisions at the CERN SPS

        Production of $\phi(1020)$ mesons is expected to play an important role in studies of the transition from confined to deconfined matter. With its zero net strangeness and its valence structure composed predominantly of $s$ and $\bar{s}$ valence quarks, the $\phi$ meson should not be sensitive to strangeness-related effects in a purely hadronic scenario, but will behave like a doubly-strange particle once partonic degrees of freedom are significant. At the CERN SPS, the energy dependence of the $\phi$ rapidity distribution is known to display a puzzling behavior.  In $p+p$ interactions, the width $\sigma_y$ of the $\phi$ rapidity spectrum follows a trend similar to that of other particles(i.e., $\pi^\pm$, $K^\pm$, and $\bar{\Lambda}$ in both $p+p$ and Pb+Pb collisions), while for central Pb+Pb reactions, it displays a much faster increase as a function of collision energy (EPJC 80, 2020, 199). No information on this phenomenon in any intermediate-size system was available up to now.

        In this talk, first results on $\phi$ meson production in central $^{40}$Ar+$^{45}$Sc collisions are presented. These are obtained through the $\phi \rightarrow K^+K^-$ decay channel using the $tag-and-probe$ method adapted from LHCb and ATLAS experiments. The $p_T$-integrated rapidity distributions, total $\phi$ multiplicities and hidden strangeness over pion ($\phi/\pi$) ratios are shown as a function of collision energy and system size from $p+p$ up to central Pb+Pb reactions. The puzzling energy dependence of $\sigma_y$, and the comparison between $\phi$ and kaon production including STAR and ALICE data on $p+p$, $d+$Au, Cu+Cu, Au+Au, and Pb+Pb reactions will be explicitly addressed in the talk.

        Speaker: Łukasz Rozpłochowski (Institute of Nuclear Physics Polish Academy of Sciences)
    • Track4-Bulk&Phase: 5 talks Room Bruxelles (Palais de la Musique et des Congrès)

      Room Bruxelles

      Palais de la Musique et des Congrès

      Convener: Francesco Becattini (Università di Firenze)
      • 118
        Entropy production and dissipation in spin hydrodynamics: Relativistic quantum-statistical approach

        Motivated by the evidence of spin polarization of matter produced in relativistic heavy ion collisions, there is a growing interest in developing relativistic hydrodynamics for spin-polarized media. This interest is mostly inspired by the previous successes of relativistic hydrodynamics in describing the collective behavior of the quark-gluon plasma. In this talk, I will present the preliminary outcomes of a quantum-statistical-based approach to relativistic spin hydrodynamics and discuss key findings in comparison to standard spin hydrodynamics, along with its future potential (arXiv:2309.05789).

        Speaker: Asaad Daher (IFJ-PAN Krakow Poland)
      • 119
        Spin alignment of vector mesons by glasma fields

        Recent measurements of large spin alignment of vector mesons beyond the expectation from vorticity may imply substantial spin correlation of the constituent quark and antiquark led by fluctuating strong-interaction forces. We explain how spin alignment of vector mesons can be induced by background color fields. Our study is based on the quantum kinetic theory of spinning quarks and antiquarks and incorporates the relaxation of the dynamically generated spin polarization. The spin density matrix of vector mesons is obtained by quark coalescence via the Wigner function and kinetic equation. We estimate the magnitude of such local correlations in the glasma model of the preequilibrium phase of relativistic heavy ion collisions. The dominant longitudinal chromo-magnetic fields from the glasma intrinsically break the rotational symmetry of spin polarization for quarks and antiquarks, which yield $\rho_{00}<1/3$ for $\rho_{00}$ being the 00-th component of the spin density matrix of vector mesons. It is also found that the strength of the resulting spin alignment could be greatly enhanced and may be comparable to the experimental measurement in order of magnitude. We further propose new phenomenological scenarios to qualitatively explain the transverse-momentum and centrality dependence of spin alignment in a self-consistent framework. Our approach may be applied to not only the light mesons but also heavy mesons such as $J/\psi$ with small momenta especially in high-energy collisions.

        Speaker: Di-Lun Yang (Academia Sinica)
      • 120
        Measurement of global and local spin polarization of $\Lambda$ and $\bar{\Lambda}$ in Au+Au collisions from the RHIC Beam Energy Scan

        A significant global spin polarization of $\Lambda$ hyperons in the first phase of RHIC Beam Energy Scan (BES-I) provided evidence of vorticity of the QGP created in heavy-ion collisions. The data also hint at a larger polarization of $\bar{\Lambda}$ than that of $\Lambda$, which can be produced by a strong late-stage magnetic field sustained by the medium. A decisive experimental test of this splitting is highly significant, as it could reveal valuable information about the electric conductivity of the QGP [1]. On the other hand, the local polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons are predicted to be different due to the polarization induced by the gradient of baryonic chemical potential (analogous to the electric field) and called baryonic spin Hall effect. This effect is expected to be observable through the energy dependence of the angular modulation of the net polarization [2], $P_{y,z}^{net}=P_{y,z}^\Lambda-P_{y,z}^{\bar{\Lambda}}$, as measured by $P_{z}^{net}sin\left(2\phi_\Lambda-2\Psi_2\right)$ and $-P_y^{net}cos\left(2\phi_\Lambda-2\Psi_2\right)$, where $\Psi_2$ is the second-order event-plane.

        We present results of $\Lambda$ global polarization as a function of centrality, transverse momentum, and rapidity in Au+Au collisions at $\sqrt{s_{NN}}$=7.7, 11.5 and 14.6 GeV from second phase of the RHIC Beam Energy Scan (BES-II) with the upgraded STAR detectors. We also present local polarization measurements in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7 - 27 GeV from BES-II. Our measurements can provide important insights into the late-stage magnetic field sustained by the QGP, as well as spin Hall currents possibly created in a highly dense baryonic environment.

        [1]L. McLerran, V. Skokov, Nucl. Phys. A 922, 184 (2014).
        [2]B. Fu et al, arXiv: 2201.12970 (2022).

        Speaker: Qiang Hu
      • 121
        Spin polarization of fermions at local equilibrium: second order gradient expansion

        Relativistic heavy-ion collisions provide a unique oppotunity to study spin polarization of fermions. In the past decade, a lot of progress has been made regarding to the spin polarization of $\Lambda$ hyperon, both at experimental and theoretical level. Polarizations induced by first order gradient quantities, such as the thermal vorticity tensor, have been widely discussed and successfully explained the $\Lambda$'s global polarization. However, the $\Lambda$'s polarization along the beam direction still remains a puzzle, which is known as the "spin sign puzzle" in heavy-ion collisions. In this work, we focus on fermions at local equilibrium in a relativistic fluid. We derive, for the first time, the spin polarization induced by second order derivatives of the four-temperature vector. As a consequence, gradients of the thermal vorticity and the thermal shear tensor also have sizable contributions to the polarization, which may provide a solution of the spin sign puzzle.

        Speaker: Xin-Li Sheng (INFN Firenze, Italy)
      • 122
        Investigation of early magnetic field and angular momentum in ultrarelativistic heavy-ion collisions via D$^{∗+ }$-meson spin alignment with ALICE

        Heavy quarks, i.e. charm and beauty, are produced at the initial stage of heavy-ion collisions, on a time scale shorter than the medium formation time, and are sensitive to the initial angular momentum of the system and the magnetic field produced perpendicular to the reaction plane (defined by the impact parameter direction and beam direction) in non-central heavy-ion collisions. In the presence of a large angular momentum and initial magnetic field, the charm quark can be polarised. The quark polarisation is expected to be transferred to the hadron during the hadronisation process. Experimentally, the heavy-flavour polarisation can be probed by measuring the spin density matrix element of spin-1 hadrons (as the D$^{*+}$ meson). Any deviation of the $\rho_{00}$ parameter from ⅓ can be attributed to the spin alignment of the D$^{*+}$ meson.

        We will present the first measurement of the $\rho_{00}$ parameter of D$^{*+}$ meson in Pb--Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02~$TeV, exploiting the large data sample collected by the ALICE Collaboration during the LHC Run 2. A comparison with the ${\rm J}/\psi$ polarisation measurement will also be reported to investigate the effect of the magnetic field.
        Moreover, the $\rho_{00}$ parameter of D$^{*+}$ mesons measured in high-energy pp collisions will also be presented, including the first studies with Run 3 data. In this case, the measurement is performed also for D$^{*+}$ mesons originating from B-meson decays. As vector mesons which decay from scalar B mesons, they are expected to be longitudinally polarised due to the helicity conservation in weak decays.

        Speaker: Himanshu Sharma (INFN Padova)
    • 10:10 AM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Track1-LF: 5 talks Room Madrid (Palais de la Musique et des Congrès)

      Room Madrid

      Palais de la Musique et des Congrès

      Convener: Prof. Katarzyna Grebieszkow (Warsaw University of Technology, Faculty of Physics)
      • 123
        Analysis of charged kaon flow in Ag+Ag collisions registered with HADES

        Charged kaons – mesons containing one (anti)strange quark – are predicted to be good probes of the Equation of State (EoS) of nuclear matter and possible changes of basic properties of kaons (like mass and decay constant) in hot and dense nuclear matter [1, 2]. These effects can be studied by comparing measured data to model calculations and the anisotropies of the azimuthal angle (flow) are expected to be particularly sensitive to them. Previous flow analyses of kaons, K$^-$ in particular, were hampered by limited statistics [3].

        The High Acceptance Di-Electron Spectrometer (HADES) [4] Collaboration carried out Ag+Ag collisions at beam energy of 1.58 GeV/nucleon and collected an unprecedented number of 10 billion events. This allows to study the flow of K$^+$ and K$^-$ mesons with statistical errors smaller than before. Together with the high acceptance of the HADES setup, the analysis could significantly advance our understanding of the properties of hot and dense nuclear matter.

        In this contribution, the preliminary results on transverse flow of K$^+$ and K$^-$ mesons emitted from Ag+Ag collisions measured with HADES will be presented as maps of $v_{1,2}(p_T, y)$. The contribution will also include the corresponding raw $(p_T, y)$ distribution and an overview of efficiency challenges specific to the measurement of flow.


        [1] T. Song et al. (PHSD), Phys. Rev. C 103, 044901 (2021)
        [2] C. Hartnack et al. (IQMD, HSD), Phys. Rep. 510, 119 (2012)
        [3] V. Zinyuk et al. (FOPI), Phys. Rev. C 90, 025210 (2014)
        [4] G. Agakichiev et al. (HADES), Eur. Phys. J. A 41 243 (2009)

        Speaker: Jan Orliński (Faculty of Physics, University of Warsaw)
      • 124
        Strangeness production in fixed-target collisions at LHCb

        The LHCb SMOG system provides the unique opportunity to study strangeness production in fixed-target collisions at the LHC. Studies of trangeness production in high-energy fixed-target collisions provides information on hadronization and serve as important inputs to models of particle production in cosmic rays. Recent results on strangeness production in fixed-target proton-nucleus collisions will be presented, including studies hyperon production and polarization.

        Speaker: Chiara Lucarelli (Firenze)
      • 125
        Dependence of net-hyperon production at mid-rapidity on beam energy and its implication on baryon number carrier

        The conventional picture of baryon number is that each valence quark inside a baryon carries 1/3 unit of baryon number. However, an alternative picture exists where the center of a Y-shaped topology of gluon fields, called the baryon junction, carries 1 unit of baryon number. Previous analysis of net-proton yield at mid-rapidity from the Beam Energy Scan program phase-I (BES-I) at RHIC showed that it depends on the beam rapidity exponentially, with a slope parameter of $0.64 \pm 0.05$. Within the baryon junction scenario, the net-hyperon yield at mid-rapidity should show a similar dependence, as junctions are flavor blind. This study aims to test this prediction by analyzing published data from BES-I program. We observe that net-hyperon yields, after correcting for strangeness production suppression, adhere to the expected exponential form. Furthermore, the fitted slope parameters for net-$\Lambda$, net-$\Xi$ and net-$\Omega$ are similar, in favor of the baryon junction picture. Conventional models, such as Pythia, are unable to reproduce such stopping behavior, highlighting the limitations of existing models, most of which lack the inclusion of baryon junction dynamics.

        Speaker: Chun Yuen Tsang (Brookhaven National Laboratory, Kent State University)
      • 126
        Strange Hadron Production at High Baryon Density

        Strange hadrons have been suggested as sensitive probes for the medium properties of the nuclear matter created in heavy-ion collisions. At few-GeV collision energies, the formed medium is dense and baryon-rich due to the baryon stopping. Since strange hadrons are produced near or below the threshold, their yields, especially the excitation function of multi-strange (anti-)hyperons, may provide strong constraints on the equation-of-state (EoS) of high baryon density matter.

        In this presentation, recent results on strange hadron production in Au + Au collisions at $\sqrt{s_{\rm{NN}}}$ = 3.0, 3.2, 3.5, 3.9 and 4.5 GeV with the fixed-target mode from the STAR experiment will be presented. These results include the transverse mass spectra, rapidity density distributions, particle ratios, and their centrality dependence of strange hadrons ($K^{\pm},~K^0_S,~\phi,~\Lambda, ~\Xi^-$). These results will be compared with those from higher collision energies and physics implication will be discussed by comparing to the thermal and transport model calculations.

        Speaker: Hongcan Li
      • 127
        Measurement of charged and neutral kaons in Ar+Sc collisions at NA61/SHINE experiment

        NA61/SHINE is a large-acceptance fixed-target experiment located at the CERN SPS. The main physics goals of the NA61/SHINE ion program are the study of the properties of the onset of deconfinement and the search for signatures of the critical point of strongly interacting matter. These goals are pursued by performing an energy (beam momentum 13$A$-158$A$ GeV/$c$) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) scan. In addition, the experiment performs dedicated hadron production measurements relevant to neutrino and cosmic ray physics.

        The experiment has recently reported an unexpected excess of charged over neutral $K$ meson production in central Ar+Sc collisions at 11.9 GeV center-of-mass energy per nucleon pair, which amounts to (23.3 ± 5.5)% at mid-rapidity. In this contribution, rapidity and transverse mass spectra and total multiplicity of $K^{+}$, $K^{-}$, and $K^{0}_{S}$ mesons, as well as charged over neutral K meson production ratio in Ar+Sc collisions will be presented.  The obtained results will be compared to the charge and neutral kaon production in different colliding systems measured by the NA61/SHINE experiment, model predictions, and measurements performed by the other experiments.

        Speaker: Tatjana Šuša (Ruđer Bošković Institute)
    • Track2-HF&Q: 5 talks Room Rome (Palais de la Musique et des Congrès)

      Room Rome

      Palais de la Musique et des Congrès

      Convener: Antonio Uras (IPNL Lyon)
      • 128
        J/$\psi$ photoproduction and polarization in peripheral Pb-Pb collisions with ALICE

        Ultrarelativistic heavy-ion collisions generate a powerful electromagnetic field that produces photonuclear reactions. These processes have been extensively studied in ultraperipheral collisions, in which the impact parameter is larger than twice the nuclear radius. Recently, coherent $J/\psi$ photoproduction has been observed in nucleus–nucleus (A–A) collisions with nuclear overlap, based on the measurement of an excess of $J/\psi$ production with respect to hadron-production expectations in the very low transverse momentum ($p_{\rm T}$). Such quarkonium measurements provide valuable insights on the nuclear gluon distribution at low Bjorken-x and high energy. In addition, they can shed light on the theory behind photon-induced reactions in A–A collisions with nuclear overlap, including possible interactions of the measured probes with the formed and fast expanding quark–gluon plasma. In order to confirm the photoproduction origin of the very low $p_{\rm T}$ $J/\psi$ yield excess, polarization measurement is a golden observable. It is expected that the produced quarkonium would keep the polarization of the incoming photon due to $s$-channel helicity conservation. ALICE can measure inclusive and exclusive quarkonium production down to $p_{\rm T}$ = 0, at forward rapidity (2.5 < $y$ < 4) and midrapidity (|$y$| < 0.9). In this contribution, new preliminary measurement of the y-differential cross section and the first new polarization analysis at the LHC of coherently photoproduced $J/\psi$ in peripheral Pb–Pb collisions will be presented. Both measurements are conducted at forward rapidity in the dimuon decay channel. These results will be discussed together with the recent results on coherent $J/\psi$ photoproduction as a function of centrality at both mid and forward rapidities. Comparison with models will be shown when available.

        Speaker: Dukhishyam Mallick (IJCLab, PHE/ALICE, Orsay)
      • 129
        Study of charm and beauty production in hadronic collisions via muon measurements at forward rapidity with ALICE

        Measurements of the production of open heavy-flavour hadrons and their semileptonic decays in high-energy heavy-ion collisions give unique access to the transport properties of heavy quarks (charm and beauty) in the quark-gluon plasma (QGP). This includes their mass-dependent in-medium energy loss, their degree of thermalisation and their in-medium hadronisation mechanisms. Charm and beauty measurements in small collision systems, pp and p--Pb, serve as important test of perturbative QCD calculations. They also provide the possibility to investigate cold nuclear matter effects in the nuclear medium and represent the baseline to study the QGP and quantify hot-medium effects in heavy-ion collisions. Measurements in these collision systems gained additional interest due to the possibility of observing, in high-multiplicity collisions, final-state effects typically attributed to the presence of the QGP in Pb--Pb collisions. The origin of these effects is still under active investigation.

        Open heavy flavours are also studied with ALICE through the semimuonic decays of charm and beauty hadrons. In this contribution, recent results of the azimuthal anisotropy of open heavy-flavour hadron decay muons in high-multiplicity p--Pb collisions at forward ($2.03 < y_{\rm CMS} < 3.53$) and backward ($-4.46 < y_{\rm CMS} < -2.96$) rapidities are discussed and compared with other experimental measurements, as well as with model calculations. The results provide new insights into the collective-like behaviour observed in small collision systems and impose stringent constraints on models.

        In addition, in the LHC Run 3, the new Muon Forward Tracker (MFT) adds vertex capabilities to the forward muon spectrometer, providing a unique way to discriminate muons from charm- and beauty-hadron decays. A first look at the measurement of muons from charm- and beauty-hadron decays, separately, in pp collisions at $\sqrt{s}$ = 13.6 TeV and Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.36 TeV collected with the upgraded ALICE apparatus is reported.

        Speaker: Maolin Zhang
      • 130
        Heavy flavor production under a strong magnetic field

        The strong magnetic field created in high energy nuclear collisions will affect the dynamical processes in the QCD medium, especially the heavy quark production that happens in the initial stage of the collisions. In this talk, I will discuss the heavy quark production cross section for the elementary process $gg\to Q\bar Q$ at leading order and the corresponding transverse momentum distribution in nucleus-nucleus collisions in both strong magnetic field and weak field limit. The main difference between these two extremes is whether dimension reduction of quark phase space happens and this will contains the production concentrated in a very narrow energy region above the threshold. Since the translation invariance is broken, the production becomes anisotropic in magnetic field. It would be interesting to observe these effects in the experiment.
        Ref: arXiv 2401.17559

        Speaker: Shile Chen (Tsinghua University)
      • 131
        Prospects for heavy flavor physics and commissioning of the tracking system in Run-24 with sPHENIX at RHIC

        sPHENIX is an exciting new experiment recently constructed at the Relativistic Heavy Ion Collider (RHIC) that will allow for the study of high precision heavy flavor (HF) observables of the Quark-Gluon Plasma (QGP), with capabilities not previously available at RHIC. The tracking system of sPHENIX is made up of four detectors working together in a hybrid streaming mode, which are the MAPS vertex detector (MVTX), intermediate silicon tracker (INTT), time projection chamber (TPC), and TPC outer tracker (TPOT). sPHENIX also includes a large acceptance, hermetic calorimeter system which features the first barrel hadronic calorimeter at RHIC. This state-of-the-art system enables the study of high statistics, unbiased heavy flavor samples, including fully reconstructed heavy flavor jets with high precision. The first sPHENIX physics run is scheduled to begin in April 2024, following a commissioning run in 2023. In this talk, we will present the progress made in the commissioning of the tracking system with collision data, the roadmap towards the first HF physics results at sPHENIX, and performance projections for the entire HF physics program.

        Speaker: Huan Huang (UCLA Physics and Astronomy)
      • 132
        Prospects for open heavy-flavour and quarkonium measurements with NA60+

        The NA60+ experiment, proposed for data taking in the next years, aims to investigate the high baryochemical potential region of the QCD phase space diagram, exploiting the large intensity of CERN SPS beams.
        By studying rare probes via a beam-energy scan with PbPb and p-A collisions in the interval 6.3 < $\sqrt{s_{NN}}$ < 17.3 GeV, NA60+ will have the possibility to access the high $\mu_{B}$ region of the QCD phase diagram.

        In this talk, we will focus on the prospects for measurements of hidden and open charm. Open charms will be measured in their decays into charged hadrons, reconstructed from tracks in the silicon detectors of the vertex telescope.
        High-precision measurements of the yield of $D^{0}$, $D^{+}$ and $D_{s}^{+}$ mesons, and of $\Lambda_{c}^{+}$ baryons, will allow us to constrain the transport properties of the QGP and the charm-quark hadronisation.
        Charmonium states will be accessed from their dimuon decay, reconstructed by matching muon tracks in the vertex telescope and in the muon spectrometer. The J/$\psi$ and $\psi$(2S) measurements at various collision energies will allow us to identify the onset of charmonium suppression in a deconfined medium, correlating this observation with the temperature of the system, as measured, always by NA60+, via thermal dimuons.
        NA60+ will also investigate the hadronic decay of strange hadrons and hypernuclei production and the corresponding performance studies will be presented.

        Finally, we will discuss the competitiveness and complementarity of NA60+ in the landscape of the experiments foreseen at other facilities in the next decade.

        Speaker: Roberta Arnaldi (INFN Torino (Italy))
    • Track3-Res&Hyp Room Londres 1 (Palais de la Musique et des Congrès)

      Room Londres 1

      Palais de la Musique et des Congrès

      Convener: Prof. Bedangadas Mohanty (National Institute of Science Education and Research)
      • 133
        Clusters as a prove of the equation-of-state of strongly interacting matter

        Authors: S. Gläßel, V. Kireyeu, V. Voronyuk, M. Winn, J. Aichelin, G. Coci, C. Blume, and E. Bratkovskaya

        We investigate the influence of the equation-of-state (EoS) of strongly interacting hadronic and partonic matter created in heavy-ion collisions on the light cluster and hypernuclei production within the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) microscopic transport approach (PHQMD) [1-5]. The PHQMD is a microscopic n-body transport model based on the QMD propagation of the baryonic degrees of freedom, where the clusters are formed via 'potential', i.e. by potential interactions between nucleons and hyperons, and recognized by by the Minimum Spanning Tree (MST) algorithm which is identifying bound clusters by correlations of baryons in coordinate space. Additionally, 'kinetic' mechanisms for deuteron production is incorporated by catalytic hadronic reactions accounting all isospin channels of the various $\pi NN\leftrightarrow \pi d$, $NNN\leftrightarrow N d$ reactions which enhances deuteron production as well as considering the quantum nature of the deuteron by mean of its finite size modelled by the finite-size excluded volume effect in coordinate space and projection of relative momentum of the interacting pair of nucleons on the deuteron wave-function in momentum space, leads to a strong reduction of d production, especially at target/projectile rapidities [4].

        Whereas in the previous PHQMD calculations we employed a static interactions between nucleons we include now a {\bf momentum dependence interaction}. The parameters of momentum dependent potential are fitted to the ”optical” potential (i.e. Schr\"odinger equivalent potential $U_{SEP}$), extracted from elastic scattering data in pA reactions. The potential grows up to $E_{kin}\sim 1.5$ GeV and then decreases.

        We observe that a static and a momentum dependent interactions, which yield for cold matter the same equation-of-state, influence the observables in heavy-ion reactions in a quite different way. We discuss the influence on flow coefficients, $v_1$ and $v_2$, of different clusters as a function of rapidity, on the $p_T$- transverse momentum spectra as well as on the fragment yield. Finally we compare our results to the HADES and STAR-BES data and find a strong sensitivity of the flow coefficient, especially of elliptic flow coefficient $v_2$ on the momentum dependence of the potential.

        Moreover, to clarify the origin of the deuteron production in heavy ion collisions from SIS to RHIC energies we propose a method to distinguish experimentally between the different possible production mechanisms.

        [1] J. Aichelin, E. Bratkovskaya, A. Le F\'evre, V. Kireyeu, V. Kolesnikov, Y. Leifels, V. Voronyuk and G. Coci, Phys. Rev. C101 (2020) 044905 [arXiv:1907.03860 [nucl-th]].
        [2] S. Gläßel, V. Kireyeu, V. Voronyuk, J. Aichelin, C. Blume, E. Bratkovskaya, G. Coci, V. Kolesnikov and M. Winn, Phys.Rev. C 105 (2022) 014908 [arXiv:2106.14839 [nucl-th]].
        [3] V. Kireyeu, J. Steinheimer, J. Aichelin, M. Bleicher and E. Bratkovskaya, Phys. Rev. C 105 (2022) 044909 [arXiv:2201.13374 [nucl-th]].
        [4] G. Coci, S. Gläßel, V. Kireyeu, J. Aichelin, C. Blume, E. Bratkovskaya, V. Kolesnikov and V. Voronyuk, Phys. Rev. C 108 (2023) 014902 [arXiv:2303.02279 [nucl-th]].
        [5] V. Kireyeu, G. Coci, S. Gläßel, J. Aichelin, C. Blume and E. Bratkovskaya, [arXiv:2304.12019 [nucl-th]].

        Speaker: Prof. Elena Bratkovskaya (GSI, Darmstadt & Frankfurt Uni.)
      • 134
        Unveiling the dynamics of little-bang nucleosynthesis

        High-energy nuclear collisions provide a unique site for the synthesis of both
        nuclei and antinuclei at temperatures of kT ≈ 100 − 150 MeV. In these little
        bangs of transient collisions, a quark-gluon plasma (QGP) of nearly vanishing
        viscosity is created, which is believed to have existed in the early universe
        within the first few microseconds after the Big Bang. Analyses of identified
        particles produced in these little bangs based on the statistical hadronization
        model for the QGP have suggested that light (anti)nuclei are produced from
        the QGP as other hadrons and their abundances are little affected by later
        hadronic dynamics. Here, we find a strong reduction of the triton yield by
        about a factor of 1.8 in high-energy heavy-ion collisions based on a kinetic
        approach that includes the effects of hadronic re-scatterings, particularly that
        due to pion-catalyzed multi-body reactions. This finding is supported by the
        latest experimental measurements and thus unveils the important role of
        hadronic dynamics in the little-bang nucleosynthesis.

        Speaker: kaijia sun (Institute of Modern Physics, Fudan University)
      • 135
        Hypernuclei and $\Xi^{-}$ measurements in Ag+Ag Collisions at $\sqrt{S_{NN}}$ = 2.55 GeV with HADES

        In the scope of the FAIR Phase-0 physics program, the HADES collaboration recorded 13.7 billion Ag(1.58A GeV)+Ag events. With an available energy of 2.55 GeV in binary nucleon nucleon collisions, the lightest hadrons containing strangeness are produced at their free nucleon nucleon threshold energy. Therefore, they are ideal probes to investigate medium effects due to their steep excitation function.

        In this contribution, we present preliminary results on the production and lifetime measurements of ${}^{3}_{\Lambda}$H and ${}^{4}_{\Lambda}$H hypernuclei which are reconstructed via their weak two-body decay channels ${}^{3}_{\Lambda}$H -> ${}^{3}$He + $\pi^{-}$ and ${}^{4}_{\Lambda}$H -> ${}^{4}$He + $\pi^{-}$. The separation of signals from the combinatorial background is based on the observed weak decay topologies evaluated with the help of an artificial neural network (ANN). For both hypernuclei a lifetime measurement with sophisticated systematic uncertainty estimations is performed to contribute to the world data of hypernuclei lifetimes. Furthermore, we present measurements of multi-strange hyperons which are produced far below their free nucleon nucleon threshold energy and reconstructed using similar analysis techniques. All presented results are discussed with respect to the available world data.

        Speaker: Dr Simon Spies (Goethe-University Frankfurt)
      • 136
        Multiplicity dependence of Hyperon and Hypertriton Production in Zr+Zr and Ru+Ru collisions at $\sqrt{s_\mathrm{NN}} = 200\, \mathrm{GeV}$

        In heavy-ion collisions, the production mechanism of hypernuclei, bound states of hyperons and nucleons, is still not fully understood. Recent theoretical model calculations show that a systematic measurement of the multiplicity dependence of yield ratios, such as $^{3}_{\Lambda}\mathrm{H}/\Lambda$ and $\mathrm{S}_{\rm 3}=(^{3}_{\Lambda}\mathrm{H}/^{3}\mathrm{He})/(\Lambda/\mathrm{p})$, can provide strong distinguishing power between different production mechanisms and offer insights into the possible connection between hypernuclei production yields and their internal structure. In 2018, STAR recorded a huge sample of about 4 billion minimum bias events from Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV, enabling a detailed investigation of the multiplicity dependence of hyperon and hypertriton production.

        In this presentation, we present new measurements on hyperons ($\Lambda, \bar{\Lambda}$ and $\Xi^{-}, \bar{\Xi}^{+}$) and hypertriton, including their transverse momentum ($p_\mathrm{T}$) spectra and $p_\mathrm{T}$-integrated yields ($\mathrm{d}N/\mathrm{d}y$), in four different centrality classes of Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. The hyperon yields will be compared to those in Au+Au collisions to study the system size dependence of strangeness production. The yield ratios of $^{3}_{\Lambda}\mathrm{H}/\Lambda$ and $\mathrm{S}_{3}$ will be shown as a function of multiplicity and compared with model calculations. Physics implications on hypernuclei production mechanism as well as Y-N interaction will be discussed.

        Speaker: Dongsheng Li
      • 137
        Production of light nuclei in Au+Au collisions with the STAR BES-II program

        The production mechanism of light (anti-)nuclei in heavy-ion collisions can be either by the thermal model or the coalescence model. By studying the yields and ratios of light (anti-)nuclei, we can gain insight into their production mechanism and physical properties of the expanding system at freeze-out. Furthermore, the enhancement in the light nuclei compound ratios such as $N_{t}N_{p}/N_{d}^{2}$ and $N_{^3He}N_{p}/N_{d}^{2}$ from the coalescence baseline, has been suggested as a potential probe to search for the critical phenomena in the QCD phase diagram. This enhancement might be a consequence of the enhanced baryon density fluctuations when the system is in vicinity of the critical point or the first-order phase transition. In the first phase of the Beam Energy Scan (BES-I) program at RHIC, an enhancement relative to the coalescence baseline of the light nuclei yield ratio ($N_{t}N_{p}/N_{d}^{2}$) is observed in the most central Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV with a combined significance of 4.1$\sigma$. The large datasets ($\sim 10\times$BES-I) taken by the STAR BES-II with enhanced detector capabilities will greatly improve the precision of the new measurements.

        In this talk, we will present the centrality and energy dependence of transverse momentum ($p_T$) spectra of $p$, $\bar p$, $d$, $\bar d$, and $^{3}He$ in Au+Au collisions at BES-II energies of $\sqrt{s_{NN}}$ = 7.7 -- 27 GeV. We will also report the centrality and energy dependence of integrated particle yields ($dN/dy$) and mean $p_{T}$ ($\langle p_{T} \rangle$) of light nuclei. We will discuss the centrality and $p_T$ dependence of the coalescence parameters ($B_{2}(d)$ and $B_{3}(^3He)$). The physics implications of these results will be discussed.

        Speaker: Yixuan Jin
    • Track4-Bulk&Phase: 5 talks Room Bruxelles (Palais de la Musique et des Congrès)

      Room Bruxelles

      Palais de la Musique et des Congrès

      Convener: Fuqiang Wang (Purdue University)
      • 138
        Initial conditions and bulk viscosity effects on $\Lambda$ polarization in high-energy heavy ion collisions

        The $\Lambda$ polarization is a crucial probe of the gradients of velocity and temperature in the quark-gluon plasma generated in heavy-ion collisions. However, it is still not systematically used to tune hydrodynamic models. In this talk, we investigate the influence of different initial conditions and parametrization of the bulk viscosity on $\Lambda$ polarization, showing that they affect the local polarization significantly. These results highlight the impact that the use of local Lambda polarization can have on refining theoretical models. Finally, we compare our results, including feed-down corrections, with experimental data from high-energy heavy-ion collisions at STAR and ALICE, and demonstrate the crucial role of bulk viscosity in generating the correct sign of longitudinal polarization at LHC energies.

        Speaker: Andrea Palermo (Stony Brook University)
      • 139
        Hyperon polarization along the beam direction in pPb collision at CMS

        The observation of hyperon polarization along beam direction ($P_z$) in nucleus-nucleus collisions has revealed the relationship between collective flow and the complex vortical structures of the quark-gluon plasma (QGP). With the high-statistics data collected by the CMS experiment, we present the first $P_z$ results in proton-lead collisions at $\sqrt{s_{NN}}= 8.16$ TeV over a wide transverse momentum range for $\Lambda$ and $\bar{\Lambda}$ particles at low- and high-multiplicity events. The measured $P_z$ signal can shed light on the mechanism of spin polarization in QGP as well as the origin of collectivity in small collision systems.

        Speaker: Chenyan Li
      • 140
        Differential measurements of $\phi$-meson global spin alignment in Au+Au collisions at STAR

        The STAR collaboration observed a significant global spin alignment ($\rho_{00}$) signal for $\phi$-mesons in Au+Au collisions using the data from the BES-I[1] which cannot be explained by conventional mechanisms, but may be attributable to the influence of a $\phi$ meson force field [2-6]. In this talk, we present differential measurements of $\phi$-meson global spin alignment using the STAR detector in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 14.6 and 19.6 GeV from the second phase of the Beam Energy Scan at RHIC (BES-II). This study aims to clarify the source of the $\phi$-meson $\rho_{00}$ signal using increased statistics available from BES-II and detector upgrades to STAR after BES-I. The first rapidity ($y$) dependent $\rho_{00}$ results for $\phi$-mesons will be shown, alongside new centrality and transverse momentum $(p_{T})$ dependent measurements. The results presented in this talk will help understand the potential link of global spin alignment to vector meson fields and their roles in the evolution of nuclear matter.

        [1] STAR Collaboration., Nature \textbf{614}, 244–248 (2023)
        [2] X.L. Sheng et al., Physical Review D \textbf{101}, 096005 (2020).
        [3] X.L. Sheng et al., Physical Review D \textbf{105}, 099903 (2022).
        [4] X.L. Sheng et al., Physical Review D \textbf{102}, 056013 (2020).
        [5] X.L. Sheng et al., Physical Review Letters \textbf{131}, 042304 (2023).
        [6] X.L. Sheng et al., Physical Review C \textbf{108}, 054902 (2023)

        Speaker: Gavin Wilks
      • 141
        Measuring the Global Spin Alignment of $\phi$ meson in Heavy Ion Collisions by STAR

        In non-central heavy-ion collisions, a large orbital angular momentum is produced. A part of the orbital angular momentum can polarize the quarks and anti-quarks, hence the vector mesons, inside the medium. Recently, STAR measured the global spin alignment of $\phi$(1020) and $K^{*}$(892) mesons in Au+Au collisions from the RHIC Beam Energy Scan I (BES I) program [1]. The global spin alignment, quantified by the $\mathrm{00}^{th}$ coefficient of the spin density matrix, $\rho_{00}$, is measured by a fit to the acceptance and efficiency corrected $\phi$ meson yield versus polar angle ($\theta^{*}$) between the daughter kaon in the parent’s rest frame and the orbital angular momentum direction. In this talk, we present an alternative approach to extract $\rho_{00}$ by utilizing the $\langle \mathrm{cos}^2 \theta^{*} \rangle$ as a function of pair-invariant mass instead of analyzing the $\phi$ meson yields in $\mathrm{cos} \theta^{*}$ bins. We use a data-driven method to correct for acceptance and efficiency. We report new analysis from this method and discuss physics implications.

        [1] M. Abdallah et al. (STAR Collaboration), Nature 614, 244–248 (2022).

        Speaker: Charles Robertson
      • 142
        Magnetic field effect on hadron yield ratios and fluctuations in a hadron resonance gas

        We study the influence of an external magnetic field on hadron yields and fluctuations in a hadron resonance gas by performing calculations within an updated version of the Thermal-FIST package. The presence of magnetic field has a sizable influence of several yield ratios involving both strange and non-strange hadrons. In particular, the enhanced $p/\pi$ ratio can be probed through centrality dependence in heavy-ion collisions. By attributing the centrality dependence of the $p/\pi$ ratio in Pb-Pb collisions at 5.02~TeV measured by the ALICE Collaboration entirely to the magnetic field, we estimate its maximal strength at freeze-out. The magnetic field also enhances various conserved charge susceptibilities, which is consistent with recent lattice QCD data and is driven in the HRG model by the increase of hadron densities. We put these results in the context of measurements of hadron fluctuations and correlations.

        Speaker: Volodymyr Vovchenko (University of Houston)
    • 12:30 PM
      Lunch box Hall


    • Excursions: Wine road in Alsace (<25 pers+?)
    • Excursions: City + boat tour
    • Excursions: European Parliament (35+75 pers, >14h40)
    • IAC meeting
    • Plenary-Overviews Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Peter Braun-Munzinger (EMMI/GSI)
      • 143
        Precision measurements of net-proton number fluctuations in Au+Au collisions at RHIC

        The main goal of the RHIC beam energy scan program (BES) is to study the strongly interacting nuclear matter phase structure and search for the possible QCD critical point in high-energy nuclear collisions. Over more than a decade, the scan (BES-I and BES-II) covered a wide range of collision energy, from $\sqrt{s_\mathrm{NN}}$ = 3.0 GeV to 200 GeV corresponding to a wide range of baryonic-chemical potential $\mu_B$ = 750 MeV to 25 MeV. The STAR detector, with some crucial upgrades, was the main apparatus used in the scan. Observables, for studying the physics of collectivity, chirality, criticality, involving light/strange hadrons, leptons, correlations, (hyper-)nuclei have been measured with the highest precision to date.

        In this talk, we will focus on the physics of phase boundary and QCD critical point. Specifically, new BES-II data on collision energy and centrality dependence of proton, anti-proton and net-proton cumulants, up to the 4$^{\mathrm{th}}$ order, in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 7.7, 9.2, 11.5, 14.6, 17.3, 19.6 and 27 GeV, will be presented. The new experimental results will be discussed within the framework of non-critical model calculations.

        Speaker: Prof. Yifei ZHANG (USTC)
      • 144
        Spin polarization in relativistic heavy ion collisions
        Speaker: Xu-Guang Huang (Fudan University)
      • 145
        Hadronisation mechanisms
        Speaker: Prof. Vincenzo Greco (University of Catania, INFN-LNS)
    • 10:00 AM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Plenary-Overviews: Hypernuclei, Nuclei and Resonances Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Conveners: Prof. Francesca Bellini (University of Bologna and INFN), Prof. Francesca Bellini (University of Bologna and INFN Bologna)
      • 146
        Strange resonances and exotic states
        Speaker: Anders Garritt Knospe
      • 147
        Hypernuclei production at RHIC and their properties
        Speaker: Yuanjing Ji (Lawrence Berkeley National Laboratory)
      • 148
        Nuclei and hypernuclei production at the LHC
        Speaker: Chiara Pinto
      • 149
        Measurement of nuclei radii in heavy ion collisions
        Speakers: Giuliano Giacalone (Universität Heidelberg), Giuliano Giacalone (Universität Heidelberg)
    • 12:30 PM
      Lunch break Room Étoile

      Room Étoile

    • Plenary-Overviews: Open charm, beauty and Quarkonia Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Mr Gines MARTINEZ (Subatech CNRS/IN2P3 - IMT Atlantique - Nantes Universite)
      • 150
        Open charm and beauty production
        Speakers: Zaida Conesa del Valle (IJCLab (CNRS/IN2P3, Université Paris-Saclay)), Zaida Conesa del Valle (CERN)
      • 151
        Hydrodynamisation of charm quarks in heavy ion collisions
        Speaker: Stefan Floerchinger (Friedrich-Schiller-Universität Jena)
      • 152
        Measurements of quarkonia production
        Speaker: Laure Massacrier (IJClab)
      • 153
        Theoretical aspects of quarkonia production in heavy ion collisions
        Speaker: Jiaxing Zhao (SUBATECH)
    • 4:00 PM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Plenary-Overviews: QCD phase diagram, Critical point and interferometry Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Tetyana Galatyuk
      • 154
        Experimental search on QCD critical point
        Speakers: Yu Zhang (Central China Normal University), Yu Zhang (Central China Normal University)
      • 155
        Available theoretical tools in search for the Critical Point of the QCD phase diagram
        Speaker: Adam Bzdak
      • 156
        Study of hadron two-body and three-body interactions with femtoscopy
        Speaker: Raffaele Del Grande (Technical University of Munich)
      • 157
        Molecular states with charm: insights from vacuum and finite-temperature analyses

        This talk explores recent results in the study of molecular states with both open and hidden charm. Employing effective-field theories that incorporate heavy-flavor degrees of freedom and implement heavy-quark spin symmetry, significant progress has been made in generating bound and resonant states through unitarization techniques. Special attention will be given to the heavy-light sector, elucidating the double pole structure of the D$^{0*}$(2300) state as well as the D$_{s}^{0*}$(2317). In the hidden charm sector, the discussion will delve into exotics, like the X(3872), highlighting differences from the compact state interpretation. Furthermore, the feasibility of extracting relevant information from femtoscopy measurements will be discussed. A final part will cover the properties of molecules at a finite temperature in the context of heavy-ion collision phenomenology and how the molecular states can melt in such a medium.

        Speaker: Juan Torres-Rincon (Universitat de Barcelona)
    • 7:30 PM
      Social dinner Pavillon Joséphine

      Pavillon Joséphine

      Parc de l'Orangerie, Av. de l'Europe, 67000 Strasbourg
    • Plenary-Overviews Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Jean-Yves Ollitrault (IPhT Saclay)
      • 158
        Flow in light ion collisions
        Speaker: Shengli Huang (Stony Brook University)
      • 159
        Collectivity in high energy proton proton collisions
        Speaker: You Zhou (Niels Bohr Institute, University of Copenhagen)
      • 160
        Progress towards understanding flow in small systems

        I will review recent progress in understanding collective phenomena in small system collisions. After discussing strong indications for the dominance of final state effects for generating signals of collectivity, I will review the important role of the longitudinal structure in small systems, ranging from 3He+Au to ultraperipheral Pb+Pb collisions.
        I will touch on the applicability of hydrodynamics, comment on models that describe dense and dilute regions differently, and discuss the status of hard probes in small systems.

        Speaker: Bjoern Schenke (Brookhaven National Laboratory)
    • 10:00 AM
      Coffee break Hall Berckheim

      Hall Berckheim

    • Plenaries-Highlights: Prospects Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Silvia Masciocchi (Universität Heidelberg & GSI)
      • 161
        LHC upgrades
        Speaker: Jochen Klein (CERN)
      • 162
        Physics program and detector technologies of ePIC at EIC
        Speakers: Carlos MUNOZ CAMACHO (IJCLab), Carlos Munoz Camacho
      • 163
        Prospects for strangeness and heavy flavour physics at FAIR
        Speaker: Yvonne Leifels (GSI Helmholtzzentrum für Schwerionenforschung)
      • 164
        SPS upgrades and prospects
        Speaker: Piotr Podlaski
    • 12:30 PM
      Lunch break Room Étoile

      Room Étoile

    • Plenary-Summaries: Summary presentations Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Prof. Hannah Elfner (GSI/GU Frankfurt)
      • 165
        Summary Talk – Theory
        Speaker: Jasmine Brewer
      • 166
        Summary Talk – Experiment
        Speaker: Javier Castillo Castellanos (Irfu/SPhN)
    • 3:15 PM
      Coffee Break Room Curie

      Room Curie

      Université de Strasbourg / Palais de la Musique et des Congrès

      Strasbourg, France
    • Plenaries-Highlights: Awards for Best Posters (NuPECC) and Flash talks (3 talks x 10min) Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Lijuan Ruan (Brookhaven National Laboratory)
      • 167
        Flash talk 1
      • 168
        Flash talk 2
      • 169
        Flash talk 3
      • 170
        Pictures for best poster Awards
        Speaker: Nicolas BUSSER (IPHC Strasbourg)
    • Closing session Room Curie (Palais de la Musique et des Congrès)

      Room Curie

      Palais de la Musique et des Congrès

      Convener: Lijuan Ruan (Brookhaven National Laboratory)
      • 171
        Best experimental talk: Andre Mischke’s Award
        Speaker: Prof. In-Kwon Yoo (Pusan National University)
      • 172
        Picture for the Andre Mischke Award
        Speaker: Nicolas BUSSER (IPHC Strasbourg)
      • 173
        SQM 2026 in UCLA
        Speaker: Huan Huang (UCLA Physics and Astronomy)
      • 174
        Closing speech
        Speakers: Antonin Maire (IPHC Strasbourg - CNRS), Boris Hippolyte (Université de Strasbourg - IPHC / IN2P3), christian kuhn (cnrs)