Elliptic flow from a hybrid CGC, full 3D hydro and hadronic cascade model

We investigate the robustness of the discovery of the perfect fluid through comparison of hydrodynamic calculations with the elliptic flow coefficient nu(2) at midrapidity in Au+Au collisions at root s(NN) = 200 GeV. Employing the Glauber model for initial entropy density distributions, the centrality dependence of nu(2) is reasonably reproduced by using an ideal fluid description of the early QGP stage followed by a hadronic cascade in the late hadronic stage. On the other hand, initial conditions based on the colour glass condensate model are found to generate larger elliptic flow due to larger initial eccentricity epsilon. We further predict nu(2)/epsilon at a fixed impact parameter as a function of collision energy root s(NN) up to the LHC energy.