相対論的流體力學基

1、 Collective flow is a key to check whether local thermalization is achieved.10-5 secm.f.p./c10-23 secm.f.p./c105-6/sec1022-23/sec Local thermalization of the QGP is non-trivial in H.I.C.Red-shifted(CMB)Blue-shifted(hadrons)See, e.g., Yagi, Hatsuda, Miake, Quark-Gluon Plasma (Cambridge, 2005) How doe

2、s the system respond to spatial anisotropy?Hydro behaviorSpatial AnisotropyMomentum AnisotropydN/dffNo secondary interaction02pdN/dff02p2v2xyfb = 7.5fm generated through secondary collisions saturated in the early stage sensitive to cross section (1/m.f.p.1/viscosity)v2 isZhang et al.(99)ideal hydro

3、 limitt(fm/c)v2: Ideal hydro: strongly interactingsystem0collision axistimeQGP fluidhadron gasInitial conditionModel*MC-GlauberMC-KLN (CGC)Participant eccentricityCentrality cut0-10%10-20%20-30%*H.J.Drescher and Y.Nara (2007)0collision axistimeQGP fluidhadron gasIdeal Hydrodynamics*Initial time 0.6f

4、m/cModel EoSlattice-based#1st order*T.Hirano(2002), #Lattice part : M.Cheng et al. (2008) 0collision axistimeQGP fluidhadron gasHadronic afterburnerHadronic transportmodel, JAM*Switching temperatureT=160 MeVNote: We changed switchingtemperature from 169 MeV to160 MeV to utilize lattice-basedEoS whic

5、h matches smoothly toa resonance gas model at thistemperature.*Y.Nara et al., (2000)Hybrid model works well up to pT1.5 GeV/c(1st order, dotted) and 2-3 GeV/c (lattice-based, solid)Soft EoS might have mimicked viscosity.Highly sensitive to initial models.Perfect fluid and CGC, compatible? Need more

6、studies on initial condition and viscosityAu+AuCu+CuQGP only QGP+hadron fluidsQGP fluid+hadron gasTH et al.,(05)Au+Au 200 GeVGlauber+ lattice(-motivated) EoSEccentricity fluctuation is essentialin central collisions.Centrality dependence OKViscosity would be needed forbetter description.Eager to see

7、 PID v2 data with less errors and less non-flow effectsin low pT (2 GeV/c) region. Mass dependence is o.k. from hydro+cascade. When mass splitting appears?20-30%ProtonPionMass ordering comes fromhadronic rescattering effect. Interplay btw. radial and elliptic flows.TH et al.,(08)TH and M.Gyulassy(05)Rapid increase of entropy density Hydro at work Evidence of QGP(?)Elliptic flow coefficientExtrapolation from RHIC to LHCTH et al.(07)Color Screeningcc Onset of J/y