Centrality dependence of hadronization and chemical freeze-out conditions in heavy ion collisions at \sqrt s_{NN} = 2.76 TeV

TL;DR

This paper analyzes hadron multiplicities in Pb-Pb collisions at 2.76 TeV, revealing a nearly constant hadronization temperature around 164 MeV and the impact of post-hadronization interactions on chemical freeze-out conditions.

Contribution

It introduces a correction method using UrQMD simulations to improve statistical model fits and accurately determine the hadronization temperature in heavy ion collisions.

Findings

Chemical freeze-out temperature varies with centrality, rising from central to peripheral collisions.

Post-hadronization inelastic scatterings affect the observed freeze-out temperature.

The primordial hadronization temperature is approximately 164 MeV.

Abstract

We present an analysis of hadronic multiplicities measured in Pb-Pb collisions at \sqrt s_{NN} = 2.76 TeV as a function of the collision centrality within the statistical hadronization model. Evidence is found of a dependence of the chemical freeze-out temperature as a function of centrality, with a slow rise from central to peripheral collisions, which we interpret as an effect of post-hadronization inelastic scatterings. Using correction factors calculated by means of a simulation based on the UrQMD model, we are able to obtain a significant improvement in the statitical model fit quality and to reconstruct the primordial chemical equilibrium configuration. This is characterized by a nearly constant temperature of about 164 MeV which we interpret as the actual hadronization temperature.