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

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

3. Introduction 3

4. Relativistic Heavy Ion Collision 00.6fmO(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 EM Probe Dynamical Probe? 4

5. Hard Probes From slides of X.-N. Wang @Hard Probe ’08 1) Jet Quenching 5 q-hat ~ 4-14 [GeV 2 /fm]

6. 2) Heavy Quark From slides of R. Rapp @SQM ’08 6 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 [GeV 2 /fm] (line) for rad. non-perturbative for coll.

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

8. HQ Energy Loss 8

9. 9 Collisional Energy Loss (E>>M>>T) (ET>>M 2 ) (ET<<M 2 ) (Braaten ‘91)

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

11. Langevin HQ + Hydro Model 11

12. weak coupling (pQCD) 1) Energy loss of heavy quarks HQ q-hats > LQ q-hats  indicates collision (Armesto ’06, Wicks ’07) (Caron-Huot ‘08) 12 Heavy Quarks in Medium DominanceExperimentHigher order Radiation (g=g(T))Fast (v ~ c)Not alone× Radiation (g=g(m D ))Fast (v ~ c)?? Collision (g=g(T))Slow (v ~ 0)Not alone× Collision (g=g(m D ))Slow (v ~ 0)OK by alone? (Moore ’05, van Hees ‘05) (Aichelin ’08) (Djordjevic ’06) But even rad+coll cannot Non-Perturbative method is required

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

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

15. Initial condition available only spectral shape above p T ~ 3GeV No nuclear matter effects in initial condition No quark coalescence effects in hadronization Where to stop in coexisting phase at 1 st order P.T.  3 choices (no/half/full coexisting phase) Reliable at high pT 15 2) Comments f 0 =1.0/0.5/0.0

16. Numerical Results : HQ 16

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

18. 18 2) relaxation time T ~ 0.21GeV _

19. 19 3) pt loss

20. 20 Nuclear Modification Factor : R AA

21. 21 Elliptic Flow : v 2

22. 22 HQ Correlation pT1>pT2 & pT1>pT trig  1:trigger, 2:associate Gamma0.00.31.03.030.0 7.2fm7.1fm6.8fm6.0fm6.3fm Gamma0.00.31.03.030.0 7.0fm6.7fm6.0fm4.0fm0.6fm Gamma0.00.31.03.030.0 7.7fm 7.8fm7.7fm7.3fm Gamma0.00.31.03.030.0 7.5fm7.4fm 7.1fm4.8fm

23. 23 Numerical Results : e ±

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

25. 25 Elliptic Flow : v 2 Poor statistics, but at least consistent. (Still preliminary, PHENIX : v2~0.05-0.1 for pT~3-5GeV)

26. Conclusions and Outlook 26

27. 27 Heavy quark can be described by relativistic Langevin dynamics with a parameter predicted by AdS/CFT (for R AA ). 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.

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