Influence of the shear viscosity of the quark-gluon plasma on elliptic   flow in ultrarelativistic heavy-ion collisions
  We investigate the influence of a temperature-dependent shear viscosity over entropy density ratio eta/s on the transverse momentum spectra and elliptic flow of hadrons in ultrarelativistic heavy-ion collisions. We find that the elliptic flow in sqrt(s_NN) = 200 GeV Au+Au collisions at RHIC is dominated by the viscosity in the hadronic phase and in the phase transition region, but largely insensitive to the viscosity of the quark-gluon plasma (QGP). At the highest LHC energy, the elliptic flow becomes sensitive to the QGP viscosity and insensitive to the hadronic viscosity. 
Harri Niemi, Gabriel S. Denicol, Pasi Huovinen, Etele Molnar, Dirk H.   Rischke
nucl-th hep-ph nucl-ex