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Heavy Flavors in High Energy Nuclear Collisions

Heavy Flavors in High Energy Nuclear Collisions ZHUANG Pengfei (Tsinghua University, Beijing) ● J/Psi Suppression and Regeneration ● D Meson Correlation and Collective Flow

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Heavy Flavors in High Energy Nuclear Collisions

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  1. Heavy Flavors in High Energy Nuclear Collisions ZHUANG Pengfei (Tsinghua University, Beijing) ● J/Psi Suppression and Regeneration ●D Meson Correlation and Collective Flow I thank Jorg Hufner (Heidelberg), XU Nu (LBNL) and YAN Li, ZHU Xianglei (Tsinghua) Workshop on QCD and RHIC Physics, Hefei, July 9-12

  2. importance of heavy quarks B.Mueller, nucl-th/0404015 ●heavy quarks are produced only in the initial impact, and no extra production in the later evolutiona probe of early thermalization and a probe of QGP ●production via pQCD processrather solid ground Workshop on QCD and RHIC Physics, Hefei, July 9-12

  3. J/Psi motion in heavy ion collisions Matsui and Satz PLB178, 416(1986): J/Psi suppression as a signature of QGP formation in HI ● both initial production and regeneration ● both normal suppression and anomalous suppression Workshop on QCD and RHIC Physics, Hefei, July 9-12

  4. normal suppression NA38 mechanism: multi-scattering between J/psi and spectator nucleons R.Vogt, Phys.Rept.310, 197(1999) C.Gerschel, J.Hufner, Annu.Rev.Nucl.Part.Sci. 49, 225(1999) conclusion:nuclear absorption can well explain the J/psi yield in p-A and light nuclear collisions at SPS energy ! Workshop on QCD and RHIC Physics, Hefei, July 9-12

  5. anomalous suppression I anomalous suppression in heavy ion collisions model 1: Debye screening (Matsui & Satz, 1986) NA38 at T=0 at T≠ 0 charmonium dissociation temperature (Karsch, Kharzeev, Satz, PLB637, 75(2006) Asakawa & Hatsuda, 2004 Kaczmarek et al., hep-lat/0312015 Workshop on QCD and RHIC Physics, Hefei, July 9-12

  6. anomalous suppression II model 2: threshold model (Blaizot, Dinh, Ollitrault, PRL85, 4010(2000) model 3: comover interaction (Capella, Feireiro, Kaidalov, PRL85, 2080(2000) dynamic processes: Workshop on QCD and RHIC Physics, Hefei, July 9-12

  7. regeneration I there are about 10 pairs of c quarks in a central Au-Au collision at RHIC energy and more than 100 pairs at LHC energy very important J/\psi regeneration at high energies: in QGP in hadron gas the competition between J/\psi suppression and regeneration leads to the question: J/\psi suppression or enhancement at high energies? model 1: sudden production (Andronic, PBM, Redlich, Stachel, NPA789, 334(2007): J/\psi’s are statistically produced at T=Tc, no initial production mesons suppression at RHIC, no clear enhancement at LHC Workshop on QCD and RHIC Physics, Hefei, July 9-12

  8. regeneration II model 2: continuous production in QGP (Thews, Mangano, PRC73, 014904(2006): J/\psi’s are continuously produced in the whole QGP region including anomalous suppression no initial production * perturbative calculation with nonrelativistic Coulomb potential (Peskin, Bhanot, NPB156, 365(1979) * detailed balance model 3: two-component model (Grandchamp, Rapp, Brown, PRL92, 212301(2004): initial production + sudden regeneration the yield in central collisions is controlled by the regeneration ! Workshop on QCD and RHIC Physics, Hefei, July 9-12

  9. necessary regeneration ? heavy quark potential (Young, Shuryak, 2008): V = U, F=U-TS Schroedinger equation:J/psi dissociation temperature Td = 2.7 Tc > maximum T at RHIC. there is no big difference between SPS and RHIC ! This explains why there is no big difference between suppressions at SPS and at RHIC. regeneration looks not necessary !? Workshop on QCD and RHIC Physics, Hefei, July 9-12

  10. transverse momentum I for J/\psi yield, almost all the models – with and without the assumption of QGP and with and without regeneration mechanism – describe the observed suppression, after at least one parameter is adjusted. the transverse momentum distribution which depends more directly on the production mechanism may contain additional information about the nature of the medium and J/\psi and may help to distinguish between different scenarios. transport model (Hufner and Zhuang, PLB559, 193(2003): transport equation for J/\psi and hydrodynamics for QGP very important leakage effect ! no regeneration at SPS regeneration leakage anomalous suppression direct production & nuclear absorption as initial condition comover mechanism Workshop on QCD and RHIC Physics, Hefei, July 9-12

  11. transverse momentum II general solution of the transport equation at RHIC and LHC: Yan, Xu, Zhuang, PRL97, 232301(2006) Workshop on QCD and RHIC Physics, Hefei, July 9-12

  12. dominant regeneration at LHC rapidity dependence, a possible evidence of regeneration at RHIC ! while both initial production and regeneration are important at RHIC, the J/psi yield at LHC is characterized by the regeneration only! PHENIX, PRL98, 232301(2007) * enhanced R_AA at LHC * large V2 at LHC Liu, Xu, Zhuang: the calculation in transport model is in progress Workshop on QCD and RHIC Physics, Hefei, July 9-12

  13. near side correlation at LHC Zhu, Xu, Zhuang, PRL100, 152301(2008) * c quark motion in QGP: for strongly interacting quark-gluon plasma: ● at RHIC, the back-to-back correlation is washed out. ● at LHC, c quarks are fast thermalized, the strong flow push the D and Dbar to the near side! we take drag coefficient to be a parameter charactering the coupling strength large drag parameter is confirmed by R_AA and v_2 of non-photonic electrons(PHENEX, 2007; Moore and Teaney, 2005; Horowitz, Gyulassy, 2007). * QGP evolution: ideal hydrodynamics Workshop on QCD and RHIC Physics, Hefei, July 9-12

  14. heavy quark thermolization Greco, Ko, Rapp, 2004 ● only charm quarks (D mesons) with pt<2 GeV are thermalized ● averaged thermalization time is about 3 fm/c Workshop on QCD and RHIC Physics, Hefei, July 9-12

  15. conclusions ● charm quark thermalization only charm quarks with pt<2 GeV are thermalized averaged thermalization time is about 3 fm/c ● J/Psi RHIC: both initial production and regeneration J/\psi suppression and small V2 LHC: only regeneration J/\psi enhancement and large V2 FAIR: only initial production very small V2 the calculation at RHIC needs a quite accurate fine-tuning between the initial production and regeneration, but the case atLHC (only regeneration)orFAIR (only initial production)is quite clean. ● DDbar correlation, a signal sensitive to sQGP RHIC: back-to-back correlation disappears LHC: near side correlation Workshop on QCD and RHIC Physics, Hefei, July 9-12

  16. outlook ● medium effect on charm quark and on charmonium strongly coupled QGP, chiral symmetry restoration, critical behavior, mass, width, binding energy,...... see Lee, arXiv:08050471 ● charm quark potential between free energy F=U-TS and internal energy different dissociation temperature (from Schroedinger equation) see Young, Shuryak, arXiv:0803.2866 ● cold nuclear matter effect (initial parton rescattering) see Qiu, Vary, Zhang, PRL88, 232301(2002) ● charm quark production in QGP see Xu, NPA697, 825(2002), Ko, this workshop Workshop on QCD and RHIC Physics, Hefei, July 9-12

  17. Workshop on QCD and RHIC Physics, Hefei, July 9-12

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