Chemical freeze-out temperature in hydrodynamical description of Au+Au collisions at sqrt(s_NN) = 200 GeV

Understand

We study the effect of separate chemical and kinetic freeze-outs to the ideal hydrodynamical flow in Au+Au collisions at RHIC (sqrt(s_NN) = 200 GeV energy).

• Unlike in 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 = 150 MeV instead of T = 160 - 170 MeV motivated by thermal models.
• Unlike previously reported, this lower temperature makes it possible to reproduce the p_T-spectra of hadrons if one assumes very small initial time, tau_0 = 0.2 fm/c.