Quarkonium Transverse Momentum Distribution as a sensitive signature of QGP

1. Quarkonium Transverse Momentum Distribution as a sensitive signature of QGP ZHUANG Pengfei (Tsinghua University, Beijing) ● The J/Ψ Puzzle ● A Full Transport Approach ● Transverse Momentum Distribution International Workshop on STAR-MTD, Tsinghua University, April 12-13, 2012

2. Importance of Quarkonium

3. Debye Screening Lattice calculated free energy F for a pair of T dissociation temperature:

4. Data Puzzle: overall suppression of J/ψ is nearly identical between SPS, RHIC & LHC ! • 62 GeV Problem: Nothing New at RHIC and LHC !

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

6. Cold and Hot Nuclear Matter Effects Hot Nuclear Matter effects: 1)suppression in QGP and HG 2)regeneration in QGP and HG Hot Nuclear Matter effects Cold Nuclear Matter effects: 1)nuclear absorption 2)Cronin effect 3)shadowing effect Cold Nuclear Matter effects

7. A Full Transport Approach for Quarkonia in HIC Chen, Liu, Yan, Zhou, Zhu, Zhuang and Xu, 2005-2012 ● QGPhydrodynamics + equation of state (ideal gas or strongly coupled matter from lattice) ●quarkoniumtransport equations α: suppression β: regeneration ● analytic solution ●initial production , including CNM.

8. Dissociation Cross Section ●gluon dissociation cross section described by OPE (Bhanot, Peskin,1999): ●at finite temperature, we use the classical relation is calculated through the Schroedinger equation ●dissociation rate of at a fixed medium velocity v=0.5 and for V=U: ●regeneration rate is determined by the detailed balance

9. Valley Structure at RHIC Y.Liu, Z.Qu, N.Xu, PZ, PLB2009 the competition between initial production and regeneration leads to a minimum, a signature for the coexistence of both production mechanisms.

10. Rapidity Dependence at RHIC Y.Liu, N.Xu, PZ, JPG2010 less regeneration in forward rapidity explains the two puzzles naturally.

11. Prediction: Pt Dependence at RHIC STAR data, QM2011 high pt particles can survive in hot medium.

12. Prediction: Centrality Dependence at RHIC STAR data, QM2011 more suppression in central collisions

13. RAA ( Np) at LHC more regeneration at LHC

14. RAA ( Np) at high pt at LHC more regeneration at low pt

15. Prediction: RAA ( pt ) at LHC

16. Prediction: Averaged Transverse Momentum SPS: dominant initial production RHIC: competition between the two LHC: dominant regeneration

17. Prediction: elliptic flow at RHIC

18. Prediction: Elliptic Flow at LHC K.Zhou, N.Xu, PZ, NPA2010 our prediction at \sqrt s = 5.5 TeV and b=7.8 fm: remarkable v2 at LHC !

19. 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 CNM effect

20. 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.

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

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

23. 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

24. Conclusion While the quarkonium yield is almost identical for heavy ion collisions at SPS, RHIC and LHC, the transverse momentum distribution is sensitive to the nature of the medium and can be used to signal the QGP formation. 24