Hadronization and Hadronic Freeze-Out in Relativistic Nuclear Collisions

TL;DR

This paper investigates the hadronization process and chemical freeze-out in high-energy nuclear collisions using a hybrid model, revealing the impact of the cascade phase on particle yields and freeze-out parameters.

Contribution

It introduces a combined hydrodynamic and cascade modeling approach to analyze freeze-out conditions and proposes a method to recover true freeze-out parameters from experimental data.

Findings

Cascade phase significantly affects antibaryon yields.

Freeze-out temperature and chemical potential are shifted by the cascade.

Proposes a method to extract original freeze-out conditions from data.

Abstract

We analyze hadrochemical freeze-out in central Pb+Pb collisions at CERN SPS energies, employing the hybrid version of the Ultrarelativistic Quantum Molecular Dynamics model, which describes the transition from a hydrodynamic stage to hadrons 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 Model, to assess the effect of the cascade phase. We observe a strong effect on antibaryon yields except anti-Omega, resulting in a shift in T and mu_B of the freeze-out curve. We discuss indications of a similar effect in SPS and RHIC data, and propose a method to recover the bulk hadron freeze-out conditions.