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 ($\text{etas}$). If temperature dependence of $\text{etas}$ is parameterized as $\text{etas}=\alpha \frac{T-T_c}{T_c}+\frac{1}{4\pi }$, experimental data favor $\alpha$ in the range 0-0.2. $\alpha \ge 0.4$ is not favored by the data. Experimental data in ${\sqrt{s}}_{NN}$=200 GeV Au+Au collisions however, prefer $\alpha$=0.4.

Comments: Final version to be published in J. Phys. G. 6 pages, 6 figures