Round Table Workshop on NICA Physics Dubna,September 9-12,20091 J/Ψ Production in Heavy Ion Collisions J/Ψ Production in Heavy Ion Collisions Pengfei ZHUANG Pengfei ZHUANG Tsinghua University, Beijing Introduction Introduction J/Ψ at SPS J/Ψ at SPS J/Ψ at RHIC J/Ψ at RHIC J/Ψ at NICA J/Ψ at NICA

Round Table Workshop on NICA Physics Dubna,September 9-12,20092 ● produced only in the initial impact, and no extra production in the later evolution a probe of early thermalization and a probe of QGP ● produced via hard process rather solid ground importance of heavy quarks B.Mueller, nucl-th/ Matsui and Satz 1986: J/Ψ suppression as a signature of QGP formation in HI

Round Table Workshop on NICA Physics Dubna,September 9-12,20093 ● both initial production and regeneration ● both normal suppression and anomalous suppression J/Ψ motion in heavy ion collision hot nuclear matter effects cold nuclear matter effects

Round Table Workshop on NICA Physics Dubna,September 9-12,20094 J/Ψ at SPS: normal suppression mechanism: multi-scattering between J/Ψ and spectator nucleons mechanism: multi-scattering between J/Ψ and spectator nucleons R.Vogt, Phys.Rept.310, 197(1999) R.Vogt, Phys.Rept.310, 197(1999) C.Gerschel, J.Hufner, Annu.Rev.Nucl.Part.Sci. 49, 225(1999) C.Gerschel, J.Hufner, Annu.Rev.Nucl.Part.Sci. 49, 225(1999) conclusion: nuclear absorption can well explain the J/Ψ yield in p-A and light nuclear collisions at SPS energy ! NA38

Round Table Workshop on NICA Physics Dubna,September 9-12,20095 model 1: Debye screening (Matsui & Satz, 1986) NA38 at T=0 at T≠ 0 J/Ψ at SPS: anomalous suppression model 2: threshold model (Blaizot, Dinh, Ollitrault, 2000) model 3: comover interaction Capella, Feireiro, Kaidalov, 2000)

Round Table Workshop on NICA Physics Dubna,September 9-12,20096 J/Ψ at RHIC: regeneration 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 important J/Ψ regeneration at high energies: in QGP in hadron gas the competition between J/\psi suppression and regeneration leads to the question: J/Ψ suppression or enhancement at high energies? model 1: statistical production at Tc, no initial production Andronic, PBM, Redlich, Stachel, 2007 Andronic, PBM, Redlich, Stachel, 2007 mesons model 2: continuous production inside QGP with anomalous suppression, no initial production Thews, Mangano, 2006 Thews, Mangano, 2006 model 3: two-component model, initial production + regeneration Grandchamp, Rapp, Brown, 2004 regeneration in hadron gas is important too Bratkovskaya, Cassing, Stoecker, 2003 the competition between suppression and regeneration explains well the data the competition between suppression and regeneration explains well the data

Round Table Workshop on NICA Physics Dubna,September 9-12,20097 J/Ψ at RHIC: is regeneration necessary ? I J/Ψ puzzle 1: almost the same suppression at SPS and RHIC ! J/Ψ puzzle 1: almost the same suppression at SPS and RHIC ! Kaczmarek et al., 2003 explanation without regeneration: Schroedinger equation for c cbar with lattice potential gives the charmonium dissociation temperature: Karsch, Kharzeev, Satz, 2006 Karsch, Kharzeev, Satz, 2006 if T SPS < T RHIC <T J/Ψ, the suppression at SPS and RHIC will be the same and it explains the puzzle 1. it looks not necessary to introduce the regeneration. if T SPS < T RHIC <T J/Ψ, the suppression at SPS and RHIC will be the same and it explains the puzzle 1. it looks not necessary to introduce the regeneration. explanation with regeneration: at RHIC, stronger suppression and stronger regeneration explanation with regeneration: at RHIC, stronger suppression and stronger regeneration

Round Table Workshop on NICA Physics Dubna,September 9-12,20098 J/Ψ at RHIC: is regeneration necessary ? II J/Ψ puzzle 2: stronger suppression at forward rapidity ! J/Ψ puzzle 2: stronger suppression at forward rapidity ! explanation with regeneration: stronger regeneration at mid rapidity Liu, Xu, Zhuang, 2009 explanation with regeneration: stronger regeneration at mid rapidity Liu, Xu, Zhuang, 2009 mid-rapidity forward rapidity explanation without hot nuclear matter effects: different J/Ψ production in pA and AA from pp Kharzeev, Levin, Nardi, Tuchin, 2009 explanation without hot nuclear matter effects: different J/Ψ production in pA and AA from pp Kharzeev, Levin, Nardi, Tuchin, 2009 strong J/Ψ suppression even at T=0 !

Round Table Workshop on NICA Physics Dubna,September 9-12,20099 transport model (Hufner, Zhuang, 2003; Zhu, Xu, Zhuang, 2005): transport equation for JΨ and hydrodynamics for QGP for J/Ψ 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 and suppression mechanisms contains more information on the nature of the medium and J/Ψ and may help to distinguish between different scenarios. the transverse momentum distribution which depends more directly on the production and suppression mechanisms contains more information on the nature of the medium and J/Ψ and may help to distinguish between different scenarios. J/Ψ at SPS: transverse momentum suppression regeneration no regeneration at SPS very important leakage effect ! pt enhancement at SPS

Round Table Workshop on NICA Physics Dubna,September 9-12, J/Ψ at RHIC: transverse momentum Yan, Xu, Zhuang, 2006; Liu, Xu, Zhuang, 2009 Yan, Xu, Zhuang, 2006; Liu, Xu, Zhuang, 2009 low pt is controlled by both initial production and regeneration low pt is controlled by both initial production and regeneration high pt enhancement is induced by Cronin effect in initial production high pt enhancement is induced by Cronin effect in initial production initial production + regeneration explain both the yield and transverse momentum distribution initial production + regeneration explain both the yield and transverse momentum distribution pt broadening pt suppression strong pt suppression strong pt suppression

Round Table Workshop on NICA Physics Dubna,September 9-12, ● LHC: almost only regeneration, sensitive to hot nuclear matter RHIC: both initial production and regeneration RHIC: both initial production and regeneration the calculation needs a quite accurate fine-tuning between the calculation needs a quite accurate fine-tuning between the two production mechanisms the two production mechanisms SPS: almost only initial production SPS: almost only initial production NICA: only initial production, sensitive to cold nuclear matter NICA: only initial production, sensitive to cold nuclear matter J/Ψ at NICA: cold nuclear matter effects ● is the rapidity dependence at NICA similar to that at RHIC? 2 gluon fusion mechanism: no 2 gluon fusion mechanism: no 3 gluon fusion mechanism: yes (Kharzeev et al., 2009) 3 gluon fusion mechanism: yes (Kharzeev et al., 2009) the rapidity dependence can distinguish from the initial production mechanisms the rapidity dependence can distinguish from the initial production mechanisms ● normal vs anomalous suppression at NICA longer collision time (~1 fm), important (dominant) nuclear absorption, longer collision time (~1 fm), important (dominant) nuclear absorption, shorter life time of hot matter, weaker anomalous suppression shorter life time of hot matter, weaker anomalous suppression

Round Table Workshop on NICA Physics Dubna,September 9-12, ● pt distribution at NICA LHC: strong pt suppression due to thermalized regeneration LHC: strong pt suppression due to thermalized regeneration NICA: strong pt enhancement due to Cronin effect ( gluon multi NICA: strong pt enhancement due to Cronin effect ( gluon multi scattering ) and leakage effect ( high momentum particles can scattering ) and leakage effect ( high momentum particles can escape the hot medium ). escape the hot medium ). the life time of hot matter is short at NICA but long at RHIC and LHC, the leakage effect is therefore more important at NICA. the life time of hot matter is short at NICA but long at RHIC and LHC, the leakage effect is therefore more important at NICA. J/Ψ at NICA: others ● mixed phase at NICA the phase transition at NICA may be of first order the phase transition at NICA may be of first order life time of mixed phase fraction of anomalous suppression RHIC 4.5 fm 7% life time of mixed phase fraction of anomalous suppression RHIC 4.5 fm 7% SPS 5 fm 30% long life time of mixed phase and short life time of quark matter long life time of mixed phase and short life time of quark matter the suppression in the mixed phase becomes more the suppression in the mixed phase becomes more important at NICA ! important at NICA !

Round Table Workshop on NICA Physics Dubna,September 9-12, conclusion cold and hot nuclear mater effects on J/Ψ in high energy nuclear collisions are still not clear at NICA: 1) Transverse momentum and rapidity distributions can distinguish from J/Ψ production mechanisms: * pt enhancement due to Cronin effect and strong leakage effect * stronger suppression at forward rapidity (3 gluon fusion) or at mid rapidity (2 gluon fusion)? 2) Nuclear absorption dominates the J/Ψ suppression and anomalous suppression happens mainly in the mixed phase 3) non-thermalized J/Ψ has small (zero) elliptic flow.

Round Table Workshop on NICA Physics Dubna,September 9-12, thanks for your attention

Round Table Workshop on NICA Physics Dubna,September 9-12, centrality dependence at SPS Zhu, Zhuang, PRC67, (2003) J/psi R_AA and at SPS energy as functions of centrality and p_t can be well described by nuclear and medium absorption, without regeneration.

Round Table Workshop on NICA Physics Dubna,September 9-12, dominant regeneration at LHC while initial production and regeneration are equally important at RHIC, the J/psi yield at LHC is characterized by the regeneration only! * J/psi is controlled by regeneration * J/psi yield at LHC increases with centrality Liu, Xu, Zhuang, PLB, 2009 and QM2009 Liu, Xu, Zhuang, PLB, 2009 and QM2009

Round Table Workshop on NICA Physics Dubna,September 9-12, initial production & nuclear absorption are included in initial condition

Round Table Workshop on NICA Physics Dubna,September 9-12, near side correlation in sQGP we take drag coefficient to be a parameter charactering the coupling strength * c quark motion in QGP: * QGP evolution: ideal hydrodynamics 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! Zhu, Xu, Zhuang, PRL100, (2008) large drag parameter is confirmed by R_AA and v_2 of non-photonic electrons (PHENEX, 2007; Moore and Teaney, 2005; Horowitz, Gyulassy, 2007).