Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session FL: Mini-Symposium: The Search for a Critical Point in the QCD Phase Diagram |
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Chair: Roy Lacey, SUNY Stony Brook Room: Hilton Queen's 5 |
Friday, October 26, 2018 9:00AM - 9:30AM |
FL.00001: QCD Phase Diagram and the Critical Point Invited Speaker: Mikhail Stephanov The crucial properties of QCD vacuum -- confinement and chiral symmetry breaking -- undergo qualitative changes at sufficiently high temperatures and/or baryon densities. Determining where on the phase diagram and how the transitions between QCD phases are accomplished is the major goal of heavy-ion collision experiments as well as of theoretical efforts, including first-principle lattice calculations. Is there a critical point in QCD separating crossover from the first order transition on the boundary between quark-gluon plasma and hadron gas phases? Heavy-ion collision experiments could answer this question by focusing on universal signatures characteristic of critical phenomena. |
Friday, October 26, 2018 9:30AM - 9:45AM |
FL.00002: Measurement of the sixth-order cumulant of net-charge distributions in Au+Au collisions at &[root]sNN =200 GeV by the STAR experiment Tetsuro Sugiura
In heavy-ion collision experiments, the study of event-by-event fluctuations is a powerful tool to characterize the thermodynamic properties of the hot and dense QCD matter. According to the Lattice QCD calculations, a cross-over exists at small μB regions but there is no experimental evidence for the location of predicted cross-over. Experimentally, it is thought that up to the sixth-order cumulant and its ratio to the variance may be the signal of the cross-over. The STAR experiment published cumulants up to the fourth-order and cumulant ratios on net-charge. In addition, the fifth- and sixth-order net-charge cumulants at √sNN = 200 GeV were presented at last Quark Matter for the first time. This presentation shows updated results of net-charge cumulants from the first- to sixth-order using particle species and pT-dependent efficiency corrections for Au+Au collisions at √sNN= 200 GeV during Beam Energy Scan in 2010 and 2011. We will discuss centrality dependence of cumulants and experimental results will be compared to Poisson, NBD and UrQMD estimations. |
Friday, October 26, 2018 9:45AM - 10:00AM |
FL.00003: Measurement of azimuthal anisotropy of proton and pion in Au+Au &[root]sNN= 4.5 GeV Fixed Target Hiroki Kato The RHIC Beam Energy Scan (BES) program is proposed to search for the Quark Gluon Plasma (QGP) and for a possible Quantum Chromo Dynamics (QCD) critical point to study the nature of the phase transition from partonic to hadronic matter. Results from the CERN SPS have been used to support the hypothesis that the onset of the phase transition occurs near √sNN = 7 GeV. The lowest beam energy accessible at RHIC in collider mode is 7.7 GeV, but Fixed-Target program can achieve lower collision energy √sNN = 4.5 GeV. At low collision energy, the directed flow is expected to be large and is sensitive to the equation of state and nature of the phase transition. In this talk, we will present azimuthal anisotropies of protons and pions as a function of centrality, pT and rapidity. |
Friday, October 26, 2018 10:00AM - 10:15AM |
FL.00004: Chemical Potential Effects on Chiral Phase Transition in AdS/QCD Sean P Bartz, Theo N Jacobson The anti-de Sitter/conformal field theory (AdS/CFT) correspondence may provide useful insights into the QCD phase diagram, particularly at finite baryon chemical potential, a regime inaccessible to lattice QCD. We present a phenomenological model for the chiral phase transition based on this duality. In these models, an AdS black hole is dual to the thermodynamic properties of the quark-gluon plasma. At zero chemical potential, we reproduce the Columbia Plot, which maps the order of the chiral phase transition as a function of light and strange quark masses. We then extend this AdS/QCD model to finite chemical potential using a charged black hole. Using the simplest charged black hole metric, the chemical potential does not affect the order of the phase transition, excluding the possibility of a critical point. We also discuss methods for introducing a critical point in this type of model. |
Friday, October 26, 2018 10:15AM - 10:30AM |
FL.00005: Phenomenological models of two-particle correlations on transverse momentum in relativistic heavy-ion collisions Robert Landon Ray, Alexander M Jentsch Two-particle correlations on (pt1,pt2) constructed from the particle production in relativistic heavy-ion collisions allow unique access to soft, semi-hard and hard-scattering processes in these systems. In this talk two phenomenological models which describe these correlations are presented and the results compared to data. One model is based on an event-by-event fluctuating blast wave. The other is based on an event-by-event fluctuating color-string plus jet fragmentation approach. Both models are capable of accurately describing the measured single-particle pt distributions for minimum-bias Au+Au collisions at 200 GeV as a function of collision centrality. The models are also applied to estimates of preliminary, charged-particle correlation measurements. Overall, both of these new, phenomenological approaches are capable of qualitatively describing these correlation structures and will provide useful tools for interpreting the centrality trends in future correlation data from the RHIC. Predictions of an event-by-event hydrodynamical model (EPOS) and the fragmentation-based model (HIJING) are compared to each other and to data. |
Friday, October 26, 2018 10:30AM - 10:45AM |
FL.00006: The STAR iTPC Upgrade Robert Pak The iTPC project is a DOE approved upgrade to the STAR detector at BNL RHIC. The project involves rebuilding the readout region for the 24 inner sectors of the STAR Time Projection Chamber. The inner sectors will be outfitted with hermetic pad planes, new wire grids and higher density readout electronics, with the goal of extended rapidity range, coverage to lower pT and improved dE/dx resolution. Details of these improvements and performance results from one iTPC sector installed during the 2018 RHIC Run will be presented. |
Friday, October 26, 2018 10:45AM - 11:00AM |
FL.00007: Abstract Withdrawn |
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