Anisotropic flows and the shear viscosity of the QGP within a transport approach

Abstract

We study the build up of elliptic flow v2 and high order harmonics vn within a transport approach at fixed shear viscosity to entropy density ratio η/s and with initial state fluctuations. In particular we study the effect of a temperature dependent η/s for two different beam energies: RHIC for Au+Au at = 200 GeV and LHC for Pb + Pb at = 2.76 TeV. We find that for the two different beam energies considered the suppression of the elliptic flow and of higher harmonics v3(pT) and v4(pT) due to the viscosity of the medium have different contributions coming from the cross over or QGP phase. Moreover, we discuss the correlation between the initial spatial anisotropies ϵn and flow coefficients vn. We observe that the elliptic flow v2 is strongly correlated with initial eccentricity ϵ2. While higher harmonics v3 and v4 are weakly correlated to their asymmetry measure in coordinate space ϵ3 and ϵ4.