Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session J3: 30 Years of J/\Psi Suppression in Heavy Ion CollisionsInvited
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Sponsoring Units: GHP DNP Chair: Ramona Vogt, Lawrence Livermore National Laboratory/University of California, Davis Room: Ballroom B |
Sunday, April 17, 2016 10:45AM - 11:21AM |
J3.00001: Screening of Quarkonia in hot and dense media: historical overview and latest lattice results Invited Speaker: Frithjof Karsch Already the first lattice QCD calculations at non-zero temperature, performed around 1980, showed that the interaction among heavy (static) quarks that are emerged into a hot and dense medium of quarks and gluons is strongly modified. The heavy quark potential is screened and will not allow for the formation of bound states when the Debye screening radius becomes smaller than the typical size of heavy quark bound states. This observation has been utilized in the seminal 1986 paper by Matsui and Satz on {\it $J/\psi$ suppression by quark-gluon plasma formation} to predict the dissolution of bound states of heavy quarks at sufficiently high temperature. They established the reduction of quarkonium yields in heavy ion collisions as a sensitive tool for probing thermal properties of hot and dense matter. We discuss progress made in understanding the thermal modification of heavy quark bound states and the sequential suppression pattern, predicted for higher excited states, through refined lattice QCD calculations of temperature dependent potentials as well as through direct calculations of spectral functions. [Preview Abstract] |
Sunday, April 17, 2016 11:21AM - 11:57AM |
J3.00002: Recent results on Quarkonium production from LHC and RHIC Invited Speaker: Enrico Scomparin The study of quarkonium production in nuclear collisions at ultrarelativistic energies is a crucial tool for the determination of the properties of the Quark-Gluon Plasma (QGP) created in such collisions. After a pioneering phase at the CERN SPS, a large amount of results were obtained at the RHIC collider, at a center of mass energy per nucleon-nucleon collisions $\sqrt{s_{\rm NN}}=0.2$ TeV and, more recently, at the LHC at $\sqrt{s_{\rm NN}}=2.76$ TeV. In a QGP, the binding of the heavy quark pair (either $c\overline c$ or $b\overline b$) that forms the quarkonium states is screened by the high density of surrounding color charges, leading to a suppression of the yield of such states. At the same time, re-combination processes involving the heavy quarks may lead to a re-generation of the quarkonia that partly counterbalances their suppression. Ultimately, these studies can provide information on the temperature of the QGP and on its degree of thermalization. In this talk, after an introduction of the main physics concepts, I will review recent experimental results obtained at RHIC and LHC in the study of $c\overline c$ (J/$\psi$ and $\psi(2S)$) and $b\overline b$ ($\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$) states. Most results refer to Au-Au (at RHIC) and Pb-Pb collisions (at LHC), but also heavier (U-U) and lighter (Cu-Cu) systems were investigated as well. Prospects for future studies, and in particular first results, if available, from the LHC Run 2 at $\sqrt{s_{\rm NN}}=5.02$ TeV, will also be discussed. [Preview Abstract] |
Sunday, April 17, 2016 11:57AM - 12:33PM |
J3.00003: Phenomenology of quarkonia suppression in heavy ion collisions Invited Speaker: Michael Strickland Phenomenological model calculations of the suppression of quarkonia in heavy ion collisions have come a long way since the initial realization over 30 years ago that such states would "melt" in a deconfined quark-gluon plasma. Despite the initial promise, in the charmonia sector, it seems that is necessary to take into account initial cold nuclear matter effects, in-medium suppression due to disassociation processes, excited state feed down, and regeneration states through recombination of open charm and anti-charm in order to explain the observed suppression at both RHIC and LHC energies. In the bottomonia sector, the situation is not as complicated, due to there being much reduced initial state and recombination effects. However, in both cases, for reliable quantitative conclusions to be drawn, the calculation of the in-medium quarkonia suppression needs to take into account the full (3$+$1)-dimensional evolution of the quark-gluon plasma using relativistic hydrodynamical background models that are able to faithfully reproduce the bulk observables and to also include the non-equilibrium corrections implied by viscous hydrodynamics on the in-medium heavy quark potential itself. In this talk, I will review the various processes playing a role in quarkonia suppression. Towards the end of the talk, I will focus on the bottomonia sector which provides a much cleaner signal of in-medium suppression than the charmonia sector. [Preview Abstract] |
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