Présidents de session
Track4-Bulk&Phase
- Elena Bratkovskaya (GSI, Darmstadt & Frankfurt Uni.)
Track4-Bulk&Phase
- Marcus Bleicher (Universität Frankfurt)
Track4-Bulk&Phase
- Anar Rustamov (GSI Helmholtzzentrum für Schwerionenforschung GmbH)
Track4-Bulk&Phase
- Mesut ARSLANDOK (Yale)
Track4-Bulk&Phase
- Francesco Becattini (Università di Firenze)
Track4-Bulk&Phase
- Fuqiang Wang (Purdue University)
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...
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 $\mu_i/T < 2.5$....
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]....
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...
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...
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.
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...
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...
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,...
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....
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...
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...
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...
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...
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...
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...
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 $\Lambda$...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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 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...
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...
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...
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...
Particle correlations are powerful tools for studying quantum chromodynamics in hadron collisions. In heavy-ion collisions, azimuthal angular correlations probe collective phenomena in hot, dense, nuclear media, such as QGP. Angular correlations in small collision systems could point to QGP production or potential initial-state correlations. The LHCb experiment has the unique ability to study...
