Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session FD: New Heavy Quark Results in Heavy-Ion Physics |
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Chair: Kenneth Barish, University of California, Riverside Room: Patio |
Thursday, October 25, 2012 4:00PM - 4:36PM |
FD.00001: Heavy quarks and quarkonia at RHIC and the LHC Invited Speaker: Clint Young Heavy flavor is produced across vastly different energy ranges and at different densities at the LHC from what has been studied at the RHIC. This may lead to the study of different energy loss mechanisms and different production channels for quarkonium using these two complementary experiments. This talk will review the current understanding of heavy quark dynamics at finite temperature and then will focus on results where the quarkonium dissociation rates are exactly related to the heavy quark momentum diffusion coefficient. Finally, in-medium hadronization of quarkonium will be discussed, as well as its implications for the production of rare heavy quark bound states. [Preview Abstract] |
Thursday, October 25, 2012 4:36PM - 5:12PM |
FD.00002: Heavy Quark Flow at RHIC Invited Speaker: Maya Shimomura Measuring the azimuthal anisotropy of particles produced in relativistic heavy ion collisions is a powerful probe for investigating the characteristics of the quark-gluon plasma (QGP), which is the phase in QCD matter of de-confined quarks and gluons. The strength of the elliptic anisotropy (v2) in the momentum phase space is transferred from the geometrical anisotropy of the initial collision region because of the pressure gradient. Thus, the measured v2 reflects the equation of state of the dense matter, possibly the QGP, produced in the collisions. The measurement of heavy quarks (charm and bottom) is an especially good tool for studying QGP since these quarks are generated only early stage of the collision and subsequently propagate through the created matter. One of the most remarkable findings at RHIC is that elliptic flow is observed for heavy quark mesons as well as light quark mesons such as pions. This indicates that the heavy quarks interact with the medium more than it had been expected and heavy quarks are also sensitive to the pressure gradients driving hydrodynamic flow. In these early results, RHIC experiments were not able to distinguish electrons from c and b independently. In order to understand these medium effects in more detail it is important to measure the flow of c and b separately. Since the b has much heavier mass than c has, b should have much less flow if the flows of the heavy quarks are purely produced by hydrodynamic mechanism. Therefore, measuring c and b flow separately enable us to check if there is any mechanism other than hydro to produce the heavy quark anisotropy. With the addition of a new Silicon Vertex Detector that enables the measurement of displaced vertices, it is now possible to have flow measurement for c and b separately at RHIC-PHENIX. We will present the latest results of single electrons from heavy quark decays and the PHENIX measurement of flow for c and b separately. [Preview Abstract] |
Thursday, October 25, 2012 5:12PM - 5:48PM |
FD.00003: Heavy flavours in Pb-Pb collisions at the LHC Invited Speaker: Francesco Prino In this talk, the heavy flavour measurements performed by the LHC experiments will be reviewed and their role in the characterization of the medium created in these collisions will be discussed. Heavy-flavour hadrons, containing charm and beauty, are powerful probes of the hot and dense medium that is formed in high-energy collisions of heavy nuclei. Charm and beauty quarks are produced in partonic scatterings with high-virtuality occurring in the initial stages of the collision. Afterwards, they traverse the medium, losing energy via gluon radiation and elastic collisions with the partonic constituents. The abundant production of charm and beauty at the LHC enables to measure heavy flavour related observables in Pb-Pb collisions with unprecedented precision. The measurement of the nuclear modification factor of heavy quarks provides a benchmark for the energy loss models that are able to describe the light quark observables. Indeed, radiative energy loss models predict that quarks lose less energy than gluons (that have a larger colour charge) and that the amount of radiated energy decreases with increasing quark mass. Another observable that is sensitive to the interaction of charm and beauty quarks with the medium is the presence of anisotropic patterns in the azimuthal distribution of final state particles. In particular, the second harmonic of the Fourier expansion of the particle azimuthal distribution, called elliptic flow, $v_2$, has been measured for heavy flavour hadrons at the LHC. At low transverse momenta, a finite $v_2$ for heavy flavours in non central collisions is expected if charm and beauty quarks suffer re-scatterings in the medium, leading to their thermalization and participation to the collective motion (flow). At higher transverse momenta, a non-zero $v_2$ is anticipated as a consequence of the path length dependence of energy loss in collisions with non-zero impact parameter. [Preview Abstract] |
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