Temperature dependence of QGP viscosity over entropy ratio from hydrodynamical analysis of ALICE data in $\sqrt{s_{NN}}$=2.76 TeV Pb+Pb collisions

Abstract

Within Israel-Stewart's theory of dissipative hydrodynamics, we have analyzed ALICE data for the centrality dependence of charged particles multiplicity, elliptic flow and $p_T$ spectra in $\sqrt{s}_{NN}$=2.76 TeV Pb+Pb collisions and obtained the temperature dependence of the QGP viscosity over the entropy ratio ($\etas$). If temperature dependence of $\etas$ is parameterized as $\etas=\alpha \frac{T-T_c}{T_c}+\frac{1}{4\pi}$, experimental data favor $\alpha$ in the range 0-0.2. $\alpha \geq 0.4$ is not favored by the data. Experimental data in $\sqrt{s}_{NN}$=200 GeV Au+Au collisions however, prefer $\alpha$=0.4.