Elliptic Flow from fKLN Initial Conditions

A current goal of ultra-relativistic heavy ion collisions experiments is to verify a picture in which the two colliding nuclei can be described as two tiny disks of a Color Glass Condensate (CGC) that is the limiting state of QCD matter at very high density and energy. The searching of CGC in uRHIC experiments is strongly related to the evaluation of the η/s. In fact in viscous hydrodynamics simulations a standard Glauber initial condition leads to estimate η/s ~ 1/4π, while the fKLN initialization, which model the melting of Color Glass Condensate, leads to at least a factor of 2 larger η/s. We have found in the framework of kinetic theory that the out-of-equilibrium initial distribution described by the fKLN reduces the efficiency in building-up the elliptic flow. In particular from our work emerges that the available data on v2 are in agreement with a η/s ~ 1/4π also for fKLN initial conditions.