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Heavy Quark Diffusion in the Quark-Gluon Fluid

2008/11/26 Komaba Seminar. Heavy Quark Diffusion in the Quark-Gluon Fluid. Yukinao Akamatsu Univ. of Tokyo. Ref : Y. A., T. Hatsuda and T. Hirano, arXiv:0809.1499[hep-ph]. Outline. Introduction HQ Energy Loss Langevin HQ + Hydro Model Numerical Results : HQ

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Heavy Quark Diffusion in the Quark-Gluon Fluid

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  1. 2008/11/26 Komaba Seminar Heavy Quark Diffusionin the Quark-Gluon Fluid Yukinao Akamatsu Univ. of Tokyo Ref : Y. A., T. Hatsuda and T. Hirano, arXiv:0809.1499[hep-ph]

  2. Outline • Introduction • HQ Energy Loss • Langevin HQ + Hydro Model • Numerical Results : HQ • Numerical Results : e± • Conclusions and Outlook

  3. Introduction

  4. Relativistic Heavy Ion Collision 0 0.6fm O(10) fm CGC Glasma Hydrodynamics Hadron Rescattering Observed What ? --- medium composed of light particles (u,d,s,g) Others : jets --- very energetic light quarks and gluons : heavy quarks (c,b) --- very heavy compared to temperature : J/Psi --- almost colorless : photons --- electromagnetic interaction Hard Probes Dynamical Probe? EM Probe

  5. Hard Probes 1) Jet Quenching From slides of X.-N. Wang @Hard Probe ’08 q-hat ~ 4-14 [GeV2/fm]

  6. 2) Heavy Quark From slides of R. Rapp @SQM ’08 • pQCD radiative E-loss with upscaled transport coeff. • Langevin with elastic pQCD + resonances + coalescence • Langevin with upscaled pQCD elastic Radiation vs. Collision q-hat ~ >14 [GeV2/fm] (line) for rad. non-perturbative for coll.

  7. Hydro + J/y T. Gunji et al. PRC 76:051901,2007 From slides of T. Gunji @SQM ’08 Survival of J/Psi ~ 2Tc ? Dynamical Probes? EM Probe From slides of F.-M. Liu @SQM ’08

  8. HQ Energy Loss

  9. Collisional Energy Loss (E>>M>>T) (Braaten ‘91) (ET>>M2) (ET<<M2)

  10. Radiative Energy Loss (BDMPS) Energy Loss (E>>M) μ : Debye mass λ : mean free path

  11. Langevin HQ + Hydro Model

  12. Heavy Quarks in Medium 1) Energy loss of heavy quarks weak coupling (pQCD) (Aichelin ’08) (Moore ’05, van Hees ‘05) (Caron-Huot ‘08) • HQ q-hats > LQ q-hats • indicates collision (Armesto ’06, Wicks ’07) But even rad+coll cannot Non-Perturbative method is required (Djordjevic ’06)

  13. strong coupling (AdS/CFT) drag force (= enegy loss dE/dx) (Gubser ’06,’07, HKKKY ’06, Teaney ‘06) ,  By comparing energy density & HQ pot. 2) Model of HQ in medium relativistic Langevin equation in the rest frame of matter assume isotropic noise the only input, dimensionless relaxation time of HQ (at T=210MeV)

  14. 1) Flowchart 0 fm…. Little Bang 0.6 fm… Initial Condition (pp + Glauber) Local temperature and flow Brownian Motion Full 3D hydrodynamics QGP T(x), u(x) (Hirano ’06) Heavy Quark Spectra _ O(10)fm… c(b)→D(B)→e- +νe+π etc Electron Spectra Experiment (PHENIX, STAR ’07) time HQs in Dynamical Medium

  15. 2) Comments Initial condition <decayed electron in pp> <HQ in pp> available only spectral shape above pT~ 3GeV Reliable at high pT No nuclear matter effects in initial condition No quark coalescence effects in hadronization Where to stop in coexisting phase at 1st order P.T.  3 choices (no/half/full coexisting phase) f0=1.0/0.5/0.0

  16. Numerical Results : HQ

  17. Profile of HQ Diffusion 2 time scales : stay time and relaxation time 1) stay time  3-4 fm

  18. 2) relaxation time _ T ~ 0.21GeV

  19. 3) pt loss

  20. Nuclear Modification Factor : RAA

  21. Elliptic Flow : v2

  22. HQ Correlation pT1>pT2 & pT1>pTtrig 1:trigger, 2:associate

  23. Numerical Results : e±

  24. Nuclear Modification Factor : RAA Experimental result  γ=1-3 AdS/CFT γ=2.1±0.5

  25. Elliptic Flow : v2 Poor statistics, but at least consistent. (Still preliminary, PHENIX : v2~0.05-0.1 for pT~3-5GeV)

  26. Conclusions and Outlook

  27. Heavy quark can be described by relativistic Langevin dynamics with a parameter predicted by AdS/CFT(for RAA). • Prediction for heavy quark correlations •  More effort needed for e-h correlations • Latest experimental data for v2 seems to have larger elliptic flow •  Within our model, coalescence even at high pT is necessary ? • Theoretically, heavy quark energy loss at strong coupling should be reconsidered.

  28. To Be Continued…

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