Elliptic flow of charged and strange hadrons in PbAu collisions at 158 AGeV/c measured in CERES experiment

Differential elliptic flow of v2(pT ) for π − , K 0 , p and Λ is measured at center- of-mass energy of √ sNN=17.3 GeV near the mid-rapidity region in rather central PbAu collisions collected by the CERES/NA45 experiment at CERN. The proton v2(pT )i s ex- tracted from π + sample and particle ratios measured by NA49 experiment adapted to CERES conditions. The proton v2(pT ) data show a downward swing towards low pT with excursions into negative v2 values which was not observed earlier. The results are com- pared with corresponding measurements performed at NA49 and STAR experiments as well as with theoretical predictions from ideal relativistic hydrodynamics. The obtained results for baryons are below hydrodynamic predictions even at the kinetic freeze-out temperature of T f =160 MeV which needs introducing of a viscous hydrodynamics at the late hadronic phase.