Systematic parameter study of hadron spectra and elliptic flow from viscous hydrodynamic simulations of Au plus Au collisions at √sNN=200 GeV

Using the (2 + 1)-dimensional viscous hydrodynamic code VISH2 + 1 [H. Song and U. Heinz, Phys. Lett. B 658, 279 (2008); H. Song and U. Heinz, Phys. Rev. C 77, 064901 (2008); H. Song, Ph. D. thesis, The Ohio State University, 2009], we present systematic studies of the dependence of pion and proton transverse-momentum spectra and their elliptic flow in 200A GeV Au + Au collisions on the parameters of the hydrodynamic model (thermalization time, initial entropy density distribution, decoupling temperature, equation of state, and specific shear viscosity eta/s). We identify a tension between the slope of the proton spectra, which (within hydrodynamic simulations that assume a constant shear viscosity to entropy density ratio) prefer larger eta/s values, and the slope of the p(T) dependence of charged hadron elliptic flow, which prefers smaller values of eta/s. Changing other model parameters does not appear to permit dissolution of this tension.