Bulletin of the American Physical Society
2015 Fall Meeting of the APS Division of Nuclear Physics
Volume 60, Number 13
Wednesday–Saturday, October 28–31, 2015; Santa Fe, New Mexico
Session FB: Invited Session: Heavy Ions from the RHIC Beam Energy Scan to the LHC Run II |
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Chair: Sergei Voloshin, Wayne State University Room: Sweeney Ballroom A |
Thursday, October 29, 2015 4:00PM - 4:36PM |
FB.00001: Future Physics Opportunities in Beam Energy Scan at RHIC Invited Speaker: Nu Xu In the first phase of the beam energy scan program (BES-I) at RHIC, we have collected data from Au$+$Au collisions at the center of mass energy range from 7.7GeV to 39GeV, corresponding to the baryonic chemical potential of 420MeV to 120MeV, respectively. We have observed the disappearance of the suppression of leading hadrons at large pT, break down of the quark scaling in the identified particle elliptic flow, the net-proton directed flow slope dv1/dy shows a minimum with negative sign, and a non-monotonical behavior of the net-proton correlation function (the fourth order) at the energy less than 20GeV. All of these observations indicate that the property of the medium at high baryon density is dramatically different from that created at the RHIC top energy where the baryon density is small and partonic interactions are dominant. In this talk I will first review what we have learned in RHIC BES-I. Then I will discuss the opportunities in the future bean energy scan program in order to address key questions regarding the QCD phase structure including the illusive critical point. I will stress that adequate detector upgrades, focused at the large baryon density region, are essential for the physics program. [Preview Abstract] |
Thursday, October 29, 2015 4:36PM - 5:12PM |
FB.00002: The RHIC Beam Energy Scan: Present Challenges and Coming Opportunities Invited Speaker: Krishna Rajagopal The RHIC Beam Energy Scan is mapping the phase diagram of QCD, creating and probing quark-gluon plasma ``doped'' to varying degrees with an excess of quarks over antiquarks. Recent data from the first phase of the scan challenge us to understand intriguing non-monotonic collision energy dependence (and therefore doping dependence) of various observables. They hint at a reduction in the QGP pressure, long anticipated in collisions that form QGP at temperatures not far above the crossover region. As the collision energy is lowered, possible signs of the turning off of effects driven by the chiral anomaly, signaling the approximate restoration of chiral symmetry, have been seen. And, there are tantalizing indications of a substantial drop and a subsequent substantial rise in a fluctuation observable that is particularly sensitive to critical fluctuations and that has been predicted to do exactly that the doping increases if a critical point on the phase diagram is approached. Each of these points to opportunities for discovery in the second phase of the scan (BES-II), coming in 2019-20, with much higher statistics data at the low energies where the most tantalizing effects reside. Today, though, the ball is squarely in the theorists' court: the data demand a concerted, multifaceted, theoretical response, building a quantitative framework for modeling the salient features of lower energy heavy ion collisions. If we respond well to this present challenge, BES-II can turn today's trends and features into discoveries, conclusions, and new understanding. [Preview Abstract] |
Thursday, October 29, 2015 5:12PM - 5:48PM |
FB.00003: Heavy Ion Collisions in Run 2 at the LHC Invited Speaker: Aaron Angerami Results from LHC run 1 have provided a wealth of new information on the properties of the matter produced in relativistic heavy ion collisions. This has been facilitated by developments of new experimental methods as well with the adaptation of precision techniques developed in high energy physics. The implications of these results mean that critical physics questions must be refined, while the improving experimental capabilities suggest a larger set of tools with which to answer these questions. This talk will briefly review some of these early milestones and set the stage for how both of these issues can be addressed in the run 2. In particular, the role of reconstructed jets and jet-based observables will be explored. The first measurements utilizing an event-by-event determination of flow harmonics were also performed during run 1, and the utility of such measurements in conjunction with traditional hard probes to provide more differential probes will be discussed. Finally, the application of such techniques to a future jet detector at RHIC and how to best utilize measurements from the two facilities will be discussed. [Preview Abstract] |
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