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Rapidity dependence of J/psi production at RHIC and LHC

Rapidity dependence of J/psi production at RHIC and LHC. Yunpeng Liu (Tsinghua University). In collaboration with Zhen Qu (Tsinghua University) Nu Xu (LBNL) Pengfei Zhuang (Tsinghua University). Outline. Motivation Formalism Numerical Results Summary. Motivation. Unsolved Puzzle of.

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Rapidity dependence of J/psi production at RHIC and LHC

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  1. Rapidity dependence of J/psi production at RHIC and LHC Yunpeng Liu (Tsinghua University) In collaboration with Zhen Qu (Tsinghua University) Nu Xu (LBNL) Pengfei Zhuang (Tsinghua University)

  2. Outline • Motivation • Formalism • Numerical Results • Summary

  3. Motivation Unsolved Puzzle of Boost Invariance (BRAHMS, PRL, 88, 2002) RAA and <Pt2> of different rapidity at RHIC (PHENIX, JPG, 2007) A puzzle at RHIC (Survival probability at SPS) (Matsui, Satz, PLB, 1986)

  4. Motivation Survival probability, determined by the medium General Scenario

  5. Motivation More information from rapidity dependence (H. Satz, talk at SQM2008, arXiv:0812.3829) Rapidity dependence of <pt2> at RHIC Same effects expected at LHC if regeneration dominates. (PHENIX, JPG, 2007)

  6. Formalism Boost Invariance (BRAHMS, PRL, 88, 2002) 2+1D Ideal Hydrodynamics of the medium 2D Hydrodynamics at y=0 where Quantities at different rapidity are related by a boost. with EoS as ideal gases of partons and hadrons.

  7. Formalism transport Leakage effect Dissociation Time evolution Longitudinal streaming Thermal regeneration Leakage Effect (J. Hüfner, P. Zhuang, 2003)

  8. Formalism Solution of the transport equation Analytical Solution: where

  9. Formalism The dynamical terms Our treatment of the dynamical terms (Asakawa, Hatsuda, QM2006, lep-lat/0808034) is related to by detailed balance.

  10. Numerical Results Numerical results at mid-rapidity RHIC LHC (Data from PHENIX, JPG, 2007)

  11. Numerical Results Parameters at RHIC Rapidity dependent parameters at RHIC: Charm Quark (PHENIX, PRL, 98, 232002, 2007) The rapidity independent parameters are the same as in our previous work. (Liu, Qu, Xu, Zhuang, arXiv:0901.2757)

  12. Numerical Results Rapidity dependence of RAA and <pt2> at RHIC Initial: same medium, similar suppression. Regen: depend on charm population Total: sum of above two Initial: from initial collision and Cronin Effect Regen: from thermalized charms Total: from the competition (Data from PHENIX, JPG, 2007) Forward Middle (Data from PHENIX, JPG, 2007)

  13. Numerical Results Extrapolation from RHIC and Tevatron (Alice: Physics Performance Report, JPG,2006) Parameters at LHC Rapidity dependent parameters at LHC: Charm Quark Color Evaporation Model estimation (Vogt etal, arXiv:hep-ph/0311048) Rapidity distribution estimated from PYTHIA (Alice: Physics Performance Report, JPG, 2006) Boost invariance of the medium is assumed

  14. Numerical Results RAA and <pt2> at LHC Regeneration Dominates. Larger suppression at forward rapidity again at LHC. Same medium, same mean pt. Forward Middle

  15. Numerical Results Suppression for regeneration Initial production Regeneration Good for SPS Good for LHC

  16. Numerical Results Suppression for regeneration Numerical results of S at RHIC and LHC LHC RHIC

  17. Numerical Results LHC RHIC Ratio at RHIC and LHC (Data from PHENIX, JPG, 2007 except that errors of <pt2> is estimated from this ref)

  18. Summary Summary • Strengths • Assumptions and limitations • Both initial production and regeneration are included. • Leakage effect included. • Different rapidity regions considered together. • Both production and momentum spectrum calculated in the same method. • Shadowing effect is not considered. • Thermalization of charms. • Boost invariance of the medium. • Hydrodynamics of ideal fluid. • EoS of Ideal gas of hadrons and partons.

  19. Summary Summary • Both the rapidity dependence of RAA and that of <pt2> can be explained by the regeneration mechanism. • Signatures of regeneration dominance at LHC :

  20. (STAR, Arxiv:0904.0439) Prof. Pengfei Zhuang will talk about the Pt dependence of Raa

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