ATLAS highlights: Recent results from ATLAS
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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...
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...
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...
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...
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,...
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...
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...
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...
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)...
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 $\mu_i/T < 2.5$....
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...
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...
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...
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]....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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....
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....
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...
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...
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...
Addressing QCD processes in a first principle manner requires a real-time, nonperturbative method. It is well known that the Schwinger model [QED in (1+1) dimensions] shares many common properties with QCD, including confinement, chiral symmetry breaking, and the existence of vacuum fermion condensate. As a step in developing such an approach, we report here on fully quantum simulations, using...
The ratio between (multi-)strange and non-strange hadron yield increases with the charged particle multiplicity, revealing a smooth transition from low multiplicity pp collisions to central Pb--Pb collisions. Enhanced production of strange hadrons in heavy-ion collisions compared to pp collisions, originally proposed as a signature of QGP formation in nuclear
collisions. Recently, similar...
In ultra-relativistic heavy-ion collisions, strong electromagnetic fields arising from the Lorentz-contracted, highly charged nuclei can be approximated as a large flux of high-energy quasi-real photons that can interact via the Breit-Wheeler process to produce $e^{+}e^{-}$ pairs. The collision energy dependence of the cross section and the transverse momentum distribution of dielectrons from...
We present a unique signal of jet-induced medium response: the enhancement
of baryon-to-meson ratios for associated particles at intermediate transverse momentum around the triggered quenched jets. Since the lost energy from the jets can diffuse to large angles, we expect that such baryon-to-meson-ratio enhancement is stronger for larger distance with respect to the jet axis. Our prediction...
Measurements of azimuthal correlations provide valuable information on the properties of the system created in collisions of hadrons and nuclei at high energy. They revealed an unexpected collective behaviour in small collision systems similar to the one exhibited by the quark--gluon plasma in heavy-ion collisions. In this talk, the origin of collectivity in small collision systems, which is...
Strangeness production in heavy-ion collisions is a longstanding and actively researched topic, offering crucial insights into the properties of strongly interacting matter. The NA61/SHINE experiment at CERN SPS North Area is one of the leading experiments in this field, focusing on measuring hadron production in a wide range of collision energies and system sizes.
This talk emphasizes the...
Studying heavy-flavor production in heavy-ion collisions (HIC) can improve our understanding of parton interactions with the Quark-Gluon Plasma (QGP). Due to their significant mass, heavy quarks (charm and bottom) are mainly produced in the initial phase of high-energy HIC, when hard scatterings are prevalent, and thus experience the entire evolution of the QGP. One way to study heavy quarks...
In context of the search for the QCD critical endpoint in heavy-ion collisions, a deep understanding of the out-of-equilibrium dynamics of the system is necessary to make well-grounded predictions for signatures in final states. To this end, we investigate the dynamic critical behavior of a classical scalar field theory with $Z_2$ symmetry in the dynamic universality class of Model A in two...
Charmonia is a valuable tool for investigating nuclear matter under extreme conditions, particularly within the strongly interacting medium formed during heavy-ion collisions. At the high energies of the LHC, the regeneration process, driven by the plentiful production of charm quarks, has been found to significantly impact the observed charmonium characteristics. It is important to conduct...
We study charmonium states, J/ψ, ψ(2S), and χc1(1P) mesons in heavy ion collisions by focusing on their production from the charm and anti-charm quarks in a quark-gluon plasma by coalescence. Starting from the investigation of the difference in their internal structures or different wave functions of charmonium states, we calculate the yield and transverse momentum distributions of charmonium...
High-energy cosmic ray experiments consistently report an excess of secondary cosmic ray muons at ground level, defying predictions from prevalent high-energy interaction models: a phenomenon known as the “Muon Puzzle”. The universal enhancement of strangeness and baryon production in p-p, p-Pb, and Pb-Pb collisions seen by the ALICE collaboration [Nat. Phys. 13, 535 (2017)] could provide an...
Strangeness production in heavy-ion collisions provides crucial insights into strongly interacting matter. The ratio of charged kaons to pions serves as a signature of deconfinement, with experimental observations revealing a distinct horn structure. The Induced Surface Tension (IST) Hadron Resonance Gas Model [1] effectively describes strangeness production and the horn structure, offering...
The early stage of a heavy-ion collision is marked by rapid entropy production and the transition from a gluon saturated initial condition to a plasma of quarks and gluons. Even in the early times of the hydrodynamic evolution, the chemical composition of the QCD medium is still largely unknown. Here we study the effects of quark chemical equilibration on the (Q)GP using a novel model of...
In high-energy heavy-ion collision experiments, the study of the pre-thermalization phase known as the Glasma and its subsequent evolution into the Quark-Gluon Plasma has revealed profound insights into Quantum Chromodynamics. The Glasma, arising from the collision of ultra-relativistic heavy ions, is characterized by highly non-equilibrium color fields and huge energy densities, significantly...
The transverse energy in heavy ion collisions is one of the key observables characterizing global properties of the Quark-Gluon Plasma (QGP). The transverse energy per unit pseudorapidity (dE$_T$/d$\eta$) probes the energy carried by the medium along the longitudinal direction, providing essential information related to the initial geometry and subsequent hydrodynamic evolution of the QGP....
We calculate the tensor polarization and the resulted spin alignment of a generic vector meson in local equilibrium up to the first order in hydrodynamic gradients using thermal field theory with dissipative effects incorporated. Several new contributions, including a novel shear-induced tensor polarization (SITP), are discovered and turn out sensitive to the in-medium spectral properties of...
Quarkyonic matter is a possible realization of dense QCD matter, corresponding to a mixture of hadrons and quarks with a mixed phase in momentum space. Recently, the quantum van der Waals theory of quarkyonic matter was developed [Phys. Rev. C 108 (2023) 045202], indicating that quarkyonic regime in symmetric nuclear matter may occur at densities as low as twice the saturation density,...
Relativistic heavy-ion collisions generate extremely strong electromagnetic (EM) fields, providing an ideal environment to study the EM excitation of the vacuum. The Breit-Wheeler process, which involves the electron-position pair production via photon-photon interactions, represents the lowest-order decay mode of the QED vacuum excitation. Its expeirmental verification by the STAR experiment...
Hypernuclei are bound nuclear systems of nucleons and hyperons. The intrinsic properties of hypernuclei, such as their binding energy and lifetime, provide experimental avenues for studying the hyperon-nucleon (Y-N) interaction. The Y-N interaction, as an essential ingredient in the equation of state of high-baryon-density matter, remains poorly constrained. The precise measurement of...
Investigating strangeness production and propagation in heavy-ion collisions in the few GeV energy regime is a sensitive tool for studying the properties of matter at high baryo-chemical potential.
In this contribution, we present results on the production of strange hadrons from a total of $3\times10^9$ most active Ag(1.58$A$ GeV)+Ag events recorded with HADES and compare the measured...
sPHENIX is a next-generation, state-of-the-art particle detector at the Relativistic Heavy-Ion Collider (RHIC) that has recently taken its first dataset of 200 GeV Au+Au collisions during a commissioning run in 2023. From this inaugural dataset, the anisotropic flow (v_n) of neutral pions (pi0's) has been measured for the first time in the sPHENIX detector using the scalar product method....
Measurements at the LHC have provided evidence for collective behavior in high-multiplicity proton-proton (pp) and proton-lead (pPb) collisions through multiparticle correlation techniques. To investigate detailed properties of this collectivity, a comprehensive study of differential Fourier coefficients ($v_{n}$) in particle transverse momentum ($p_\mathrm{T}$) and event multiplicity is...
We extend the Quantum van der Waals description of nuclear matter at zero temperature to a high baryon density region by incorporating the continuous transition to quark matter in accordance with the recently proposed quarkyonic approach [1]. The nucleon-nucleon interaction parameters are fixed from the empirical properties of the nuclear ground state. The resulting equation of state exhibits...
Collective flow and energy loss are two of the most important tools to study the Quark-Gluon Plasma formed in relativistic heavy ion collisions. Collective flow is usually explored through soft particles correlations while energy loss studies normally uses hard probes, as heavy flavor quarks or jets coming from hard scattering of partons. However, the interplay between these two ways of...
Utilizing rapidity-dependent measurements to map the QCD phase diagram provides a complementary approach to traditional beam energy-dependent measurements around midrapidity. The changing nature of thermodynamic properties of QCD matter along the beam axis in heavy-ion collisions at low collision energies both motivate and pose challenges for this method. In this study, we derive the...
Thermalization of the quark gluon plasma (QGP) created in relativistic heavy-ion collisions is a crucial theoretical question in understanding the onset of hydrodynamics, and in a broad sense, a key step to the exploration of thermalization in quantum systems.
Addressing this problem theoretically, in a first principle manner, requires a real-time, non-perturbative method. To this end, we...
We study quasinormal $f−$mode oscillations in neutron star(NS) interiors within the linearized General Relativistic formalism. We utilize approximately 9000 nuclear Equations of State (EOS) using spectral representation techniques, incorporating constraints on nuclear saturation properties, chiral Effective Field Theory( $\chi$EFT) for pure neutron matter, and perturbative Quantum...
We employ a novel event-by-event multistage framework for simulating heavy-ion collisions which includes finite baryon number, electric charge, and strangeness due to fluctuations in the initial state. This novel framework generates an initial condition using the McDIPPER saturation based event generator which has been upgraded to include charge fluctuations, followed by pre-equilibrium...
The Zubarev approach of the non-equilibrium statistical operator [1] is used to account for the enhancement of the low-$p_T$ part of pion spectra by introducing an effective pion chemical potential [2]. This is an alternative to the explanation of the low-$p_T$ enhancement by resonance decays. We report on first results obtained with a newly developed thermal particle generator that implements...
Recent experimental results present collectivity also in small systems with high-multiplicity. Today these phenomena are not completely understood: it is an important question whether the presence of the QGP is necessary for the observed collectivity or not. Moreover, the connection between the experimental observables and theories is not trivial. In our phenomenological study we introduce the...
The production of strange quarks and antiquarks in high-energy collisions of
heavy ions is a significant indicator for the creation of a state of matter known
as Quark-Gluon Plasma (QGP). The QGP is characterized by the liberation of
quarks and gluons from their confinement inside hadrons. Due to their instant
decay via weak interactions, strange quarks and antiquarks are not present...
We assume a relatively weak magnetic field at $0.01-0.1 m_{\pi}^{2}$ level in the QGP. In approximate equilibrium, the quark distribution function is modified by the electromagnetic field. The quark and anti-quark tend to move back to back in the plane. As a consequence, the virtual photons are produced in the polarized states. Virtual photon polarization is characterized by coefficients...
Deciphering the hadronization process has long been a formidable challenge, in part due to its non-perturbative nature. Over the years, various phenomenological models have emerged, all attempting to unravel the complexity of hadron production. Despite their different theoretical foundations, many of these models successfully account for the average yield of hadrons. This has spurred the...
This talk presents the latest result on the energy-energy correlator using the archived ALEPH e+e- data taken at the LEP at a center of mass energy of sqrt(s) = 91.2 GeV. The energy-energy corrector presents a different way to study QCD concerning other approaches utilizing jets and (sub)structures, garnering recent increased interest in this observable in hadronic collision systems at the LHC...
The spectral functions of chiral partners should become degenerate when the QCD chiral symmetry is restored. The axial-vector spectra are experimentally more challenging to construct than those of vector mesons that directly couple to virtual photons and then to dileptons. Chiral mixing of the vector with axial-vector mesons is thus a key phenomenon to probe in-medium modifications of vector...
After four decades of measurement of strange hadrons produced in nucleus-nucleus collisions we are now at disposal of over 100 yields of K$^{\pm,0}$, $\phi$ and $\Lambda$. It's a good time to systematize them as function of available energy, $\sqrt{s_{NN}}$ and number of participant nucleons, $\langle A_\mathrm{part} \rangle_\mathrm{b}$.
However, as different collaborations used different...
The measurement of the production of hadrons containing charm or beauty quarks in proton–proton ($pp$) collisions provides an important test for perturbative quantum chromodynamics calculations ($p$QCD).
The ALICE detector allows us to perform precise measurements of non-prompt D-meson production, which are an excellent tool to investigate the production of beauty quarks in $pp$ collisions....
NA61/SHINE is a multipurpose fixed-target experiment located at CERN SPS. One of its main goals is to study the onset of deconfinement and the properties of strongly interacting matter. For this purpose, a unique two-dimensional scan in collision energy (sqrt(s_NN) = 5.1 - 17.3 GeV) and system size was performed.
Results on identified hadron spectra produced in nucleus-nucleus collisions,...
Two-particle correlation functions provide critical information about the medium created in heavy-ion collisions. Recent ALICE measurements have demonstrated large dynamical correlations between produced neutral and charged kaons in Pb--Pb collisions at $\sqrt{s_{\rm{NN}}} = 2.76 $ TeV. These integrated correlations cannot be described by conventional heavy-ion models, such as EPOS and AMPT....
The substantial mass of charm quarks makes them an ideal tool for probing the de-confined medium of quarks and gluons. These charm quarks interact with the medium, thereby carrying vital information about it, before undergoing hadronization to form heavy flavor hadrons.
In this study, we make use of the color string percolation model (CSPM) and the van der Waals Hadron Resonance Gas...
Among the most important results from Run1 and Run2 at the LHC is the observation of enhanced production of (multi-)strange to non-strange hadron yields, gradually rising from low-multiplicity to high-multiplicity pp and p--Pb collisions, reaching values close to those measured in peripheral Pb--Pb collisions. More insightful information about the production mechanism could be provided by...
One main motivation of the Beam Energy Scan (BES) program at RHIC is to search for the QCD critical point and the onset of deconfinement. Strangeness production has been suggested as a sensitive probe to the early dynamics of the deconfined matter created in heavy-ion collisions. Ratios of particle yields involving strange particles are often utilized to study various properties of the nuclear...
Quarkonium production has long been identified as one of the golden probes to study the quark-gluon plasma (QGP). The early production of heavy quarks ($c\bar{c}$ and $b\bar{b}$) make quarkonia an ideal probe to investigate the evolution of the hot and dense medium produced in ultra-relativistic heavy-ion collisions. Among many observables, the measurement of azimuthal anisotropies (expressed...
We simulate deuteron production in Pb+Pb collisions at 2.76 TeV and focus particularly on the elliptic flow. Two models for the production are compared: direct thermal production and coalescence. In coalescence, the yield of deuterons with certain momentum depends on the size of the region producing the nucleons from which the deuteron is composed. The elliptic flow also depends on how the...
Key aspects in modeling the formation of bound systems such as the deuteron in high-energy collision are the understanding of the strong interaction between nucleons and the characterization of the nucleon-emitting source, which is particularly relevant in models of nucleon coalescence. In this respect, the femtoscopy technique has proven to be a great tool to study both the particle emitting...
Compact stars (CS) are stellar remnants of massive stars. Inside CSs the density is so high that matter is in subatomic form composed of nucleons. With the increase in density of matter towards the center of the objects other degrees of freedom like hyperons, heavier non-strange baryons, and meson condensates may appear. Not only that at higher densities, the nucleons may get decomposed into...
Due to Debye-like color screening of quarkonium binding potential,
quarkonium suppression has been proposed as an important signature of
quark-gluon plasma, produced in central heavy ion collisions. However the
quarkonium production mechanism is still an unresolved question. The
production can happen through hard scattering and an intermediate Color Singlet or Color Octet states, which...
One of the important topics in strong interaction physics is the study of in-medium properties of hadrons, which has direct relevance to Heavy Ion Collision experiments. Several experiments, e.g. CERN-SPS, KEK-PS E325, RHIC-PHENIX, etc., have indicated the influence of the generated medium on the properties of the hadrons. In this work, we investigate the in-medium properties of open strange...
The sPHENIX experiment represents a novel detector system at the Relativistic Heavy Ion Collider at BNL. Its main goal is to advance our understanding of Quark Gluon Plasma and Cold-QCD by studying jet and heavy-flavor observables with a high-precision tracking system.
The sPHENIX tracking system comprises the MVTX, TPC, TPOT, and Intermediate Silicon Tracker (INTT). This poster aims to...
Anisotropic flow parameters $(v_{n})$ are important observables as they provide insight into the collecIve expansion and transport properIes of the medium produced in relaIvisIc heavy-ion collisions. Among these parameters, directed flow ($v_1$) describes the collecIve sideward motion of produced parIcles in heavy-ion collisions. It is an important probe to study the in-medium dynamics as it...
Measuring chiral partners, such as $\rm{K_1}$ and $\rm{K^*}$ mesons, whose vacuum widths are less than 100 MeV, is suitable for investigating chiral symmetry restoration in heavy-ion collisions.
According to a recent theoretical calculation, the $\rm{K_1/K^*}$ ratio in heavy-ion collisions is predicted to be substantially larger than the value obtained using the statistical hadronisation...
NA61/SHINE is a multipurpose, fixed-target experiment located at the CERN Super Proton Synchrotron (SPS). The main goal of its strong interaction program is to study the properties of the onset of deconfinement and search for the critical point.
Resonance production is one of the key observables to study the dynamics of high-energy collisions. In dense systems created in heavy...
Short-lived resonances are ideal probes to study the properties of the hadron gas phase created in heavy-ion collisions in the post-hadronization phase. Since the resonance lifetime is comparable to that of the hadron gas phase, their yields are affected by the competing rescattering and regeneration effects. These can be studied experimentally by measuring the yield ratios of resonances to...
In heavy-ion collisions, strange particles are not present before the collision, as they are absent in normal matter. Consequently, strange particles must be produced during or shortly after the collision. Therefore, the production of strange quarks serves as an important probe for the underlying physics of heavy-ion collisions.
In this project, we will investigate strangeness production...
The strongly interacting quarks and gluons plasma (QGP) phase is a must to exhibit the collective behavior. Experimental observations from heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) revealed such collective phenomena. Additionally, intriguing features like strangeness enhancement further support the existence of QGP in these...
In ultra-peripheral heavy-ion collisions (UPCs), vector meson photoproduction, e.g., $\rho^{0}$ and $J/\psi$, has been considered one of the most sensitive probes for studying the gluonic structure in heavy nuclei. The linear polarization of the photons involved in these processes can help to image the nucleus through the so-called spin interference effect in vector meson photoproduction. Many...
The comparison between the production of short-lived resonances (e.g., $K^{*}$) to non-resonances (e.g., $K$) is commonly employed to understand the role of re-scattering and regeneration processes that occur during the late stages of hadronic interactions. Additionally, the neutral ($K^{*0}$ $(d\bar{s})$) and charged ($K^{*+}$ $(u\bar{s})$) vector mesons share similar mass and isospin, but...
The main goals of relativistic heavy-ion collisions at various energies at RHIC include the study of the QCD phase structure and the properties of the quark gluon plasma. Strange hadrons have been suggested as sensitive probes to the early dynamics of the fireball created in heavy-ion collisions. Ratios of particle yields involving strange particles are often utilized to study various...
Ratios of production yields of different charm hadron species are a sensitive observable to study the hadronization process.
Recently, the ALICE Collaboration reported the production yield of charm baryons ($\Lambda_\mathrm{c}^{+}$, $\Sigma_\mathrm{c}^{0,++}$, $\Xi_\mathrm{c}^{0,+}$, $\Omega_\mathrm{c}^{0}$) relative to that of $\mathrm{D}$ mesons in proton--proton collisions.
The measured...
We study the energy deposition and thermalisation of high-momentum on-shell partons (minijets) travelling through a non-equilibrium Quark-Gluon Plasma using QCD kinetic theory. For thermal backgrounds, we show that the parton energy first flows to the soft sector by collinear cascade and then isotropises via elastic scatterings. In contrast, the momentum deposition from a minijet reaches the...
The physics of the recently observed spin polarization of Λ hyperons in heavy-ion collisions is still ambiguous and is under intense investigation. The evolution of the medium is governed by QCD. Thus, it is necessary to incorporate the equation of state (EoS) for the hot QCD medium in our theory. This can be achieved by considering an effective model with a spacetime-dependent mass. Hence, we...
There is currently no agreed-upon description of the interactions that heavy flavored hadrons undergo in the late stages of a heavy ion collision. Although a significant effort is being done to study heavy flavor creation and diffusion during the partonic evolution, the same cannot be said about the hadronic rescattering stage. This leaves open questions such as how much anisotropic flow of...
We investigate the possibility of constraining the Lambda ($\Lambda$) potential in dense nuclear matter from the $\Lambda$ directed flow ($v_1$).
The hyperon puzzle in neutron stars, extensively discussed in recent decades, refers to the problem that most of the equations of state (EOS) with hyperons are not sufficiently stiff to support the observed massive neutron stars. The presence or...
We present a comprehensive differential study of hyperon polarization in
(ultra-)central Au+Au collisions at low and intermediate energies, employing the microscopic transport model UrQMD in conjunction with the statistical hadron-resonance gas model. This study entails a complex analysis of the of the fireball dynamics and thermal vorticity field evolution. The resulting thermal vorticity...
Extensive research at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) on Pb-Pb and Au-Au collisions have helped us develop and understand the properties of the quark-gluon plasma (QGP) in heavy-ion collisions. Recent investigation suggests that QGP-droplets may occur in small collision systems such as high-multiplicity pp collisions. O-O collisions are...
The quark-gluon plasma (QGP) produced in ultrarelativistic heavy-ion collisions has exhibited properties of a mostly perfect fluid. These properties can be observed through the hydrodynamic expansion of the QGP. Experimentally, this was established by measuring azimuthal anisotropies in the final state, known as elliptic flow ($v_2$) or higher order harmonics such as triangular flow...
The ALICE experiment changed its data-taking strategy from triggered to continuous detector readout and underwent several detectors upgrades, in order to cope with the LHC Run3 luminosity increase and maximize the amount of data collected. Among the aforementioned upgrades, the installation of the new muon forward tracker (MFT) enriches the study of quarkonium production previously carried out...
This study focuses on measuring b-jet production in pp collisions at 13.6 TeV with the ALICE detector at the LHC. The accurate identification of b-jets is crucial for understanding heavy-flavor quark fragmentation. To achieve this, we apply heavy flavor tagging techniques, including track counting and the secondary vertex method. These techniques significantly enhance the precision of b-jet...
sPHENIX, the first detector to be built at the Relativistic Heavy-Ion Collider (RHIC) in over two decades, will bring unprecedented measurement capabilities at RHIC energies. One of the initial physics measurements performed by sPHENIX is that of the total charged-particle multiplicity, which utilizes two-point tracklets constructed from clusters in the Intermediate Silicon Tracker (INTT), and...
The Electron-Ion Collider (EIC) is a future particle accelerator at Brookhaven National Laboratory. It will provide physicists with high luminosity and highly polarized beams with a wide range of nuclei species at different energies, covering an extensive kinematic range, which will provide unprecedented access to the spatial and spin structure of proton, neutron, and light ions. The EIC...
We investigate the role of inelastic processes in the strongly interacting quark-gluon plasma (sQGP) within the effective dynamical quasi-particle model (DQPM). In the DQPM the non-perturbative properties of the sQGP at finite temperature $T$ and baryon chemical potential $\mu_B$ are described in terms of strongly interacting off-shell partons (quarks and gluons) with dynamically generated...
We present a novel construction of the QCD equation of state (EoS) at finite baryon density. Our work combines a recently proposed resummation scheme for lattice QCD results with the universal critical behavior at the QCD critical point. This allows us to obtain a family of equations of state in the range $0\leq \mu_B \leq 700$ MeV and $25\leq T\leq 800$ MeV, which match lattice QCD results...
Jet quenching parameter $\hat{q}$ is essential for characterizing the interaction strength between jet partons and nuclear matter. Based on the quark-meson (QM) model, we develop a new framework for calculating $\hat{q}$ at finite chemical potentials, in which $\hat{q}$ is related to the spectral function of the chiral order parameter. A mean field perturbative calculation up to the one-loop...
The $^{238}$U nucleus is well deformed with a large quadruple deformation $\beta_2=0.286$. However, its hexadecapole deformation $\beta_{\rm 4,U}$ is not well determined, mainly because it is overshadowed by the large $\beta_{\rm 2,U}$ in experimental observables that are typically sensitive to both. A recent study (Ryssens, et.al., Phys.Rev.Lett. 130, 212302) proposes a smaller $\beta_2$...
The difference between the spin alignments of $K^\ast$ and those of $\phi$ at the low collisional energies is a puzzle raised by the recent experiments. Unlike $\phi$ meson, $K^*$, carrying a unit strange charge, should react to strange potential. In this talk, I shall first convince you that the strange chemical potential is not small in a brayon-rich medium for keeping strange neutrality,...
We study the diffusion of heavy quarks in the early stages of high-energy nuclear collisions. The pre-equilibrium stage of relativistic heavy-ion collisions, commonly known as Glasma, evolves according to the classical Yang-Mills (CYM) equations. Heavy quarks are coupled to the evolving Glasma fields via relativistic kinetic theory.
We compute the momentum broadening as well as the angular...
We employ a relativistic kinetic theory model based on the GLW(de Groot - van Leeuwen - van Weert) formalism of the spin hydrodynamics with the Frenkel condition to study the local spin polarization of Λ hyperons. We calculate the Pauli-Lubanski pseudovector with the dissipative correction to the extended phase-space distribution function, obtained within a relaxation-time approximation. This...
Balance functions have been used extensively to elucidate the time evolution of quark production in heavy-ion collisions. Early models predicted two stages of quark production, one for light quarks and one for the heavier strange quark, separated by a period of isentropic expansion. This led to the notion of clocking particle production and tracking radial flow effects, which drive the...
The recent spin polarization measurement of $\Lambda$ ($\bar{\Lambda}$) hyperons by the ALICE and STAR Collaborations has created a remarkable interest in the nuclear and high energy physics community to investigate the possible sources for hyperon polarization. It is suggested that in peripheral heavy ion collisions, the initial orbital angular momentum (OAM) manifests the vorticity, which...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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,...
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...
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 $\mu_{B}$...
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,...
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...
