Charged particleʼs elliptic flow in (2+1)D viscous hydrodynamics at LHC (s=2.76 TeV) energy in Pb + Pb collision

In the Israel-Stewartʼs theory of second order hydrodynamics, we have simulated s=2.76 TeV Pb + Pb collisions. ALICE data for the centrality dependence of charged particles multiplicity, pT spectra in 0-5% collisions, centrality dependence of integrated and differential elliptic flow are analysed. Analysis indicate that while ALICE data on charged particles multiplicity or pT spectra do not demand any viscosity, viscosity is demanded by the elliptic flow data. From a simultaneous fit to all the data sets, viscosity to entropy ratio in sNN=2.76 TeV Pb + Pb collisions is extracted as, η/s=0.06±0.2.