Energy Dependence of Particle Ratios in High Energy Nucleus-Nucleus Collisions: A USTFM Approach

TL;DR

This paper uses the Unified Statistical Thermal Freeze-out Model (USTFM) to analyze particle ratios in high-energy nucleus-nucleus collisions, revealing insights into chemical freeze-out conditions and their relation to collision energy and QCD phase transition.

Contribution

The study applies the USTFM incorporating hydrodynamic flow effects to describe particle ratios and their energy dependence, highlighting the near-constant freeze-out temperature and high transparency at LHC energies.

Findings

Chemical freeze-out temperature is nearly constant beyond RHIC energies.

Chemical potential approaches zero at LHC, indicating high nuclear transparency.

Particle production is consistent with a statistical thermal model.

Abstract

We study the identified particle ratios produced at mid-rapidity in heavy ion collisions, along with their correlations with the collision energy. We employ our earlier proposed Unified Statistical Thermal Freeze-out Model (USTFM), which incorporates the effects of both longitudinal as well as transverse hydrodynamic flow in the hot hadronic system. A fair agreement seen between the experimental data and our model results confirms that the particle production in these collisions is of statistical nature. The variation of the chemical freeze-out temperature and the baryon chemical potential with respect to collision energies is studied. The chemical freeze-out temperature is found to be almost constant beyond the RHIC energy and is found to be close to the QCD predicted phase transition temperature suggesting that the chemical freeze-out occurs soon after the hadronization takes place. The vanishing value of chemical potential at LHC indicates very high degree of nuclear transparency in the collision.