Validity of the Hadronic Freeze-Out Curve

Abstract

We analyze hadro-chemical freeze-out in central Pb+Pb collisions at CERN SPS energies, employing the hybrid version of UrQMD which models hadronization by the Cooper-Frye mechanism, and matches to a final hadron-resonance cascade. We fit the results both before and after the cascade stage using the Statistical Hadronization Model, to assess the effect of the cascade phase. We observe a strong effect on antibaryon yields except anti-Ω, resulting in a shift in T and μ_B. We discuss the implications for the freeze-out curve.

5 pages, 8 figures. To appear in the proceedings of Quark Matter 2011, the XXII International Conference on Ultrarelativistic Nucleus-Nucleus Collisions