Heavy Quark and charm propagation in Quark-Gluon plasma 2009/11/25 Discussion with Prof. Blaizot Heavy Quark and charm propagation in Quark-Gluon plasma Yukinao Akamatsu Tetsuo Hatsuda Tetsufumi Hirano (Univ. of Tokyo) Ref : Y.A., T.Hatsuda and T.Hirano, PRC79,054907 (2009) Y.A., T.Hatsuda and T.Hirano, PRC80,031901(R) (2009)

Outline Introduction Langevin + Hydro Model for Heavy Quark Numerical Calculations Conclusions and Outlook Discussion

Medium composed of light particles (u,d,s,g) Introduction 0.6fm O(10) fm initial thermalization hydrodynamics hadron scattering observed Medium composed of light particles (u,d,s,g) Strongly coupled QGP (sQGP)  How can we probe it? Others : jets, J/Psi, etc Heavy quarks (c,b) --- heavy compared to temperature tiny thermal pair creation 　　　　　　　　　　　　　　　　　 no mutual interaction  Good probe !

Langevin + Hydro Model for Heavy Quark 1) Our model of HQ in medium in the (local) rest frame of matter Relativistic Langevin equation Assume isotropic Gaussian white noise the only input, dimensionless Satisfy fluctuation-dissipation theorem 2) Energy loss of heavy quarks Weak coupling (pQCD) (leading order) Poor convergence (Caron-Huot ‘08) Strong coupling (SYM by AdS/CFT  sQGP) [ for naïve perturbation] N=4 SYM theory (Gubser ’06, Herzog et al. ’06, Teaney ’06) “Translation” to sQGP (Gubser ‘07)

c(b)→D(B)→e- +νe+π etc 3) Heavy Quark Langevin + Hydro Model 0 fm…. Little Bang generated by PYTHIA 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 _ c(b)→D(B)→e- +νe+π etc O(10)fm… (independent fragmentation) Electron Spectra + …. Experiment (PHENIX, STAR ’07) time

Numerical Calculations 1) Nuclear Modification Factor & Elliptic Flow Experimental result  γ=1-3 (AdS/CFT γ=2.1±0.5) charm : nearly thermalized bottom : not thermalized Different freezeouts at 1st order P.T. γ=1-3  Much smaller elliptic flow than in experiment bottom dominant ・Initial (LO pQCD) : good only at high pT ・CNM, quark coalescence : tiny at high pT

2) Azimuthal Correlation Back to back correlation of a heavy quark pair diffusion Loss of correlation in decay products from D & B e(mid-pseudorapidity)-μ(fwd-pseudorapidity) correlation : one peak no contribution from vector meson decay IAA : quantitative measure e-μ azimuthal correlation: sensitive probe for heavy quark thermalization rate

e-h correlation (mid-pseudorapidity) : two peaks A sensitive probe but not clean … Effects we ignore : ・Hadronic interaction of associates ・Medium response to HQ propagation ・Fictitious correlation due to bulk v2 Relative angle range for IAA Near side : -0.5π≦Δφ≦0.5π Away side : 0.5π≦Δφ≦1.5π

Drag parameter cannot explain RAA and v2 simultaneously. Conclusions and Outlook Heavy quark can be described by relativistic Langevin dynamics with a drag parameter predicted by AdS/CFT (for RAA). Drag parameter cannot explain RAA and v2 simultaneously. A proposal of electron-muon correlation as a new tool to probe the heavy quark drag parameter. Possible updates for initial distribution with FONLL pQCD quark coalescence, CNM effects,・・・ (but almost done by Dr. Morino)

Backup

Weak coupling calculations for HQ energy loss γ~2.5 γ~0.2 RHIC, LHC

A Little More on Langevin HQ Fluctuation-dissipation theorem Ito discretization  Fokker Planck equation Generalized FD theorem

Notes in our model 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 mixed phase at 1st order P.T.  3 choices (no/half/full mixed phase) f0=1.0/0.5/0.0