Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session B05: RHIC Beam Energy Scan II and the QCD Critical PointInvited Live
|
Hide Abstracts |
Sponsoring Units: GHP DNP Chair: Ramona Vogt, LLNL/UC Davis |
Saturday, April 17, 2021 10:45AM - 11:21AM Live |
B05.00001: The QCD Phase Diagram - Theoretical Perspectives Invited Speaker: Jacquelyn Noronha-Hostler Unlike phase diagrams in condensed matter that can be probed in the laboratory, the QCD phase diagram can only be mapped out through both experiments and astrophysical phenomena. At low baryon densities and high temperatures it is explored both through the big bang and the little bangs produced in heavy-ion collisions. At large baryon densities, either low-energy heavy-ion experiments or neutron star mergers can be used to map out its potential phases. While the underlying theory - Quantum Chromodynamics - is known, due to the sign problem one cannot reasonably calculate the equation of state of QCD beyond small baryon densities. Here I will review the different approaches used in the description of hot and ultradense baryonic matter in and out of equilibrium, and discuss the regions in the phase diagram where heavy-ion collisions and neutron star mergers can overlap. Future perspectives are discussed to map out the phase diagram of strongly interacting matter from heavy ion collisions to neutron stars. [Preview Abstract] |
Saturday, April 17, 2021 11:21AM - 11:57AM Live |
B05.00002: Insights from the STAR Collider Program Invited Speaker: Helen Caines Quantum Chromodynamics (QCD) predicts that the phase diagram of nuclear matter has a rich structure, including that of a deconfined state of quarks and gluons at extreme temperatures and/or pressure. We have shown that we create such a state, termed the Quark-Gluon Plasma or QGP, in the medium generated by colliding heavy nuclei at ultra-relativistic velocities. Understanding the properties of the QGP and locating key features, such as the predicted first order phase transition boundary and the corresponding critical point in the QCD phase diagram, will enhance our knowledge of the universe's evolution and the structure of all visible matters. ~Experimentally we can probe different regions of the phase diagram by varying the energy of the colliding beams thus altering the initial temperature and net-baryon density of the medium produced. The first Beam Energy Scan (BES-I) took place at RHIC from 2010-2017. While intriguing hints for a first order phase transition were revealed, more precise data were needed before firm conclusions could be drawn. ~The STAR collaboration therefore proposed, and is now conducting, a second phase of the beam energy scan program (BES-II) focusing on energies below 27 GeV. The expected order of magnitude higher statistics datasets will allow STAR to perform one of the most precise explorations of the phase diagram to date. In this talk, I will briefly review the experimental progress for exploring the QCD phase structure at STAR, with a focus on the status and plans for analysis of the data taken in collider mode. Details of the fixed target program, which allows us to record data at beam energies below that that can be collided at RHIC, will be discussed in another talk in this session. [Preview Abstract] |
Saturday, April 17, 2021 11:57AM - 12:33PM Live |
B05.00003: Insights from the STAR Fixed-Target Program Invited Speaker: Daniel Cebra The beam energy scan (BES) program at RHIC has been designed to study the transition of QCD matter between a state of dense hadronic gas and that of a quark-gluon plasma. At top RHIC and LHC energies this is understood to be a continuous phase transition. However, many theoretical understandings suggest that, for matter-dominated (i.e. high baryon chemical potential) QCD matter, there should be a first-order phase transition and the end of the first-order boundary should be a critical point. Theory and results of BES-I suggest that the critical point may be located near or below the low-energy limit of the RHIC collider program. Therefore, STAR has developed a fixed-target program to complement the BES-II collider program. By steering a beam in RHIC to graze the upper edge of an internal gold target, the experiment and the accelerator have developed a conduct of operations to efficiently acquire Au+Au collisions at a series of nine energies ranging from $\sqrt{s_{NN}}$ = 3.0 to 7.7 GeV. At the low end of this energy range, the QCD matter is expected to remain in a hadronic gas state throughout the evolution of the reaction. The top end of the fixed-target energy range overlaps with the low end of the collider energy range, which allows a cross-check of the corrections required due to the energy-dependent fixed-target acceptance. Acquisition of these data was completed during operations in 2018, 2019, and 2020. Due to the time required for detailed offline calibrations, currently only some of the energies are available for physics analysis. This talk will address the insights acquired from the first results from this fixed-target energy scan and review the prospects as additional energies become available for physics analyses. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700