  We calculate initial conditions for the hydrodynamical evolution in
ultrarelativistic heavy-ion collisions at the LHC and RHIC in an improved
next-to-leading order perturbative QCD + saturation framework. Using viscous
relativistic hydrodynamics, we show that we obtain a good simultaneous
description of the centrality dependence of charged particle multiplicities,
transverse momentum spectra and elliptic flow at the LHC and at RHIC. In
particular, we discuss how the temperature dependence of the shear viscosity is
constrained by these data.

High Energy Physics - Phenomenology