Quarkonium as a Probe of QGP

1. Quarkonium Transverse Momentum Distribution as a Sensitive Signature of QGP Pengfei Zhuang (Tsinghua University, Beijing) ● The J/Ψ Puzzle ● A Detailed Transport Approach ● Transverse Momentum Distribution NN2012, San Antonio, May 27 - June 1, 2012

2. Quarkonium as a Probe of QGP heavy quarks are mainly produced in the initial impact, almost no extra production in the later evolution Matsui and Satz, 1986:J/ψ as a probe of QGP in heavy ion collisions What Is the Hot Medium Effect on Jpsi ?

3. From Dissociation to Dissociation + 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 quarkonium regeneration at high energies: in QGP in hadron gas Peter Braun-Munzinger group Thews group Rapp group mesons Problem: the competition between dissociation and regeneration may reduce the difference between SPS, RHIC and LHC !

4. J/ψ Yield at SPS, RHIC and LHC The Jpsi Yields at SPS, RHIC and LHC Have Similar Behavior ! Is There a Jpsi Observable Which Is Sensitive to the Hot Medium? • 62 GeV

5. Transverse Momentum Distribution ! Pt distribution is sensitive to the dynamics of the system and should tell us more about the nature of the medium. Data and Our Model Prediction 5

6. A Full Transport Approach for Quarkonia in HIC Yunpeng Liu, Kai Zhou, ……, Nu Xu, PZ, 2005-2012 ● QGPhydrodynamics + equation of state (ideal gas or lattice simulation) ●quarkoniumtransport equations α: suppression β: regeneration ● analytic solution both initial production and regeneration suffer from screening ! ●initial production , including CNM.

7. Dissociation Cross Section ●gluon dissociation cross section calculated by OPE (Bhanot, Peskin,1999): ●at finite temperature, we use the classical relation is calculated through the Schroedinger equation ● J/Ψdissociation rate ●regeneration rate is determined by the detailed balance

8. Charm Quark Distribution Due to interaction with the medium, charm quarks become soft in the medium, and therefore the regeneration happens mainly in the low pt region. From observed D-meson flow at RHIC, charm quarks seem to be thermalized, we take thermal distribution for charm quarks in the medium. Initial fraction and regeneration fraction for J/Ψ produced in central Pb+Pb collisions at LHC energy, with thermal charm quark distribution. for a pQCD charm quark distribution, the initial production and regeneration will behave similarly !

9. Transverse Momentum Distribution at RHIC (1) STAR data, QM2011

10. Transverse Momentum Distribution at RHIC (2) Y.Liu, Z.Qu, N.Xu, PZ, PLB2009 the competition between initial production and regeneration leads to a minimum. we need more precise data.

11. Centrality Distribution at LHC ALICE Collaboration, arXiv:1202.1383 Model Calculations: 1)Peter Braun-Munzinger group 2)Ralf Rapp group 3)Tsinghua group

12. Averaged Transverse Momentum (1)

13. Averaged Transverse Momentum (2) 1) not sensitive to the shadowing effect 2) for a pQCD charm quark distribution, the ratio behaves similarly at SPS, RHIC and LHC

14. Elliptic Flow at RHIC almost no v2 at RHIC !

15. Elliptic flow at LHC remarkable v2 at LHC !

16. Conclusion the quarkonium transverse momentum distribution is sensitive to the nature of the medium and can be used to signal the QGP formation in heavy ion collisions. 16

17. Backup

18. J/Ψ

19. Input ● medium evolution ● initial production ● regeneration

20. Charmonium in pp Collisions observation: difficult to observe ψ’ ! Ψ’ and χc decay into J/ψ: Ψ’ χc J/ψ mechanisms for quarkonium production in pp:it is difficult to describe quarkonium formation due to confinement problem 1) color evaporation model: 2) color-singlet model: 3) color-octet model:

21. Rapidity Dependence at RHIC Y.Liu, N.Xu, PZ, JPG2010 less regeneration in forward rapidity

22. Transverse Momentum Dependence at RHIC STAR data, QM2011 high pt J/psi’s are from the initial production and can survive in hot medium.

23. Centrality Distribution for High pt J/ψs at LHC

29. DD Correlation

30. 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 ATHIC III at Wuhan, October, 2010

31. Upsilon

32. Υ, a Cleaner Probe at RHIC J/ψ : the production and suppression mechanisms are complicated: there are primordial production and nuclear absorption in the initial state and regeneration and anomalous suppression during the evolution of the hot medium. Υ: 1) the regeneration can be safely neglected; 2) there is almost no feed-down forΥ ; 3) weaker shadowing effect • 32

33. Υat RHIC: RAA( pt ) Liu, Chen, Xu, Zhuang: arXiv:1009.2585,PLB2011 central Au+Au at √s=200 GeV ● strong Cronin effect

34. Υat RHIC: relation between ϒ at RHIC and J/ψ at SPS: ●no ϒ regeneration at RHIC and no J/ψ regeneration at SPS ●no ϒ(1s) suppression at RHIC no J/ψ suppression at SPS both are controlled by the Cronin effect ! Au+Au at √s=200 GeV Liu, Chen, Xu, Zhuang: arXiv:1009.2585,PLB2011

35. ATHIC III at Wuhan, October, 2010

36. Υat RHIC: RAA( Np) Y.Liu, B.Chen, N.Xu, PZ,PLB2011 for minimum bias events: PHENIX dada: RAA<0.64 (NPA2009) our result: RAA = 0.63 for V=U RAA= 0.53 for V=F ●from the comparison with data, V is close to U.

37. Υat LHC: RAA( Np) ●again, V is close to U.

38. Υat LHC: RAA( pt ) high pt is controlled by initial production !

39. Measuring RHIC Temperature by Excited ϒ States initial temperature dependence of RAA central Au+Au at √s=200 GeV Liu, Chen, Xu, Zhuang: arXiv:1009.2585,PLB2011 suppression of excited ϒ states is sensitive to the fireball temperature !

40. EoS

41. Dependence on EoS J/Psi Pt distribution at LHC where EoS plays an essential role! wQGP sQGP

42. Cold Nuclear Effect

43. Only Cold Nuclear Matter Effect ?