Chemical freeze-out temperature in the hydrodynamical description of Au+Au collisions at root S-NN=200 GeV

摘要

We study the effect of separate chemical and kinetic freeze-outs to the ideal hydrodynamical flow in An + An collisions at RHIC (root S-NN= 200 GeV energy). Unlike earlier studies we explore how these effects can be counteracted by changes in the initial state of the hydrodynamical evolution. We conclude that the reproduction of pion, proton and antiproton yields necessitates a chemical freeze-out temperature of T approximate to 150 MeV instead of T = 1.60-1.70 MeV motivated by thermal models. Contrary to previous reports, this lower temperature makes it possible to reproduce the PT spectra of hadrons if one assumes very small initial time, T-0 = 0.2fm/c. However, the PT differential elliptic flow, upsilon(2)(p(T)) remains badly reproduced. This points to the need to include dissipative effects (viscosity) or some other refinement to the model.