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Analysis of transverse momentum dependence of J/ ψ in Heavy-Ion Collisions

Analysis of transverse momentum dependence of J/ ψ in Heavy-Ion Collisions. Xingbo Zhao with R. Rapp Cyclotron Institute + Physics Department Texas A&M University College Station, USA. 24 th WWND , Apr. 10 2008. Outline. p T dependence for two-component model

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Analysis of transverse momentum dependence of J/ ψ in Heavy-Ion Collisions

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  1. Analysis of transverse momentum dependence of J/ψ in Heavy-Ion Collisions Xingbo Zhao with R. Rapp Cyclotron Institute + Physics Department Texas A&M University College Station, USA 24th WWND , Apr. 10 2008

  2. Outline • pT dependence for two-component model • Numerical results for SPS and RHIC 3. Study of RAA(pT) at high pT 4. Summary and outlook

  3. 1.0) 2-Component Model • Boltzmann Transport Equation • satisfies the homogenous equation where is from (pT indep.) with initial condition ~ =

  4. 1.1) pTdependence of direct component • Cronin effect from p-A data at SPS at SPS(RHIC) • at RHIC [Hüfner et. al. 01’]

  5. 1.1) pTDependence of Direct Component 2. Momentum dependence of dissociation rate : cylindrically expanding fireball with entropy conservation QGP Stage: i. Gluo-dissociation: Ineffective for small ii. Quasi-free: adjust to RAA(ET) at SPS Hadronic Stage: SU(4) effective theory, rate is small [Bhanot and Peskin 79’] [Grandchamp and Rap 01’]

  6. 1.1)pTDependence of Dissociation Rate • Numerical results of rates [Rapp 05’]

  7. 1.1) Leakage Effect [Blaizot and Ollitrault ’88,Karsch and Petronzio 88,Zhuang and Hüfner 01] • Leakage Effect Charmonia with high pT may travel out of fireball before freeze out and are therefore effectively subject to less suppression.

  8. 1.2) pTDependence of Coalescence Component ~ = Blastwave approximation: evaluated at hadronization transition , (same fireball as for direct component) at RHIC(SPS) [Schnedermann et. al. 93’]

  9. 1.3) Two Parametersand Two parameters adjusted to RAA(Npart)of J/ψ 1. in Quasifree cross section adjust to RAA(Npart) at SPS NA50 (Alternatively gluodiss. is used with of J/ψ) 2. Time delay in statistical equilibrium limit from RAA(Npart) at RHIC AuAu [Braun-Munzinger et. al. 00’] [Grandchamp and Rapp 02’]

  10. 2.1) RAA(ET) and <pT2>(ET) at SPS • Coalescence comp. small, as fit by suppression • Slight reduction of < pT2> due to quasifree dissociation in QGP

  11. 2.2) RAA(Npart) and <pT2>(Npart) at RHIC See also [Thews 05’],[Yan et.al. 06’],[Andronic et.al. 07’]

  12. 2.3) RAA(pT) of J/ψfor RHIC AuAu

  13. 2.4) Elliptic Flow for J/ψ from AuAu at RHIC • v2 is small for all pT

  14. 3) Study of RAA(pT) at high pT • Increasing trend of RAA(pT>5 GeV)

  15. 3.0) 4 Attempts to improve RAA(pT>5GeV) • Sensitivity on Cronin effect ( ) ? • B->J/ψ? • Formation time effect? • Gluo-dissociation rate in QGP stage?

  16. 3.1) Sensitivity on • Weak constraint for Cronin effect from d+Au at RHIC

  17. 3.2) B->J/ψ • RAA(pT) from B feeddown increase at high pT

  18. 3.3) Formation Time Effect [Gavin and Vogt 90’, Blaizot and Ollitrault 88’, Karsch and Petronzio 88’] • Effectively smaller dissociation for high pT Charmonium :Nuclear absorption, Partonic and Hadronic Suppression Rate :Formation time of Charmonia

  19. 3.3) Formation Time Effect

  20. 3.4) Gluo-dissociation rate in QGP stage

  21. 4) Summary and Outlook • Rate equation approach including suppression and regeneration for J/psi, chi_c and psi’ • Two paramters (as and ) can reproduce centrality dependence at SPS and RHIC • Resulting pt dependence consistent with data up to pt~5 GeV • Extra ingredients needed at high pt (formation time, B feeddown, Cronin) • Next : Full Boltzmann Equation with more microscopic charm quark distributions • Check In-Medium physics in more detail: lattice QCD……

  22. Thank you! (Details can be found in hep-ph/0712.2407, accepted by PLB)

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