Effect of geometrical size of the particles in a hot and dense hadron gas

TL;DR

This paper reviews existing models for incorporating baryon size effects in the equation of state of hot, dense hadron gases, identifies their shortcomings, and proposes a new thermodynamically consistent model that performs well at extreme conditions.

Contribution

The paper introduces a new thermodynamically consistent model for the excluded volume effect in hadron gases, improving accuracy at high temperatures and densities.

Findings

The new model remains valid at extremely high temperatures and densities.

It provides corrected thermodynamical variables consistent with thermodynamic principles.

Comparison shows the new model outperforms previous approaches.

Abstract

Incorporation of the finite size of baryons into the equation of state (EOS) of a hot and dense hadron gas (HG) in a thermodynamically consistent manner has been a much studied problem. We first review its current status. Various models have been proposed in order to account for the repulsive force generated by the hard-core geometrical size of the baryons resulting in an excluded volume effect in the EOS. We examine the criterion of the thermodynamical consistency of these models and summarize their shortcomings. In order to remove the shortcomings, we propose a new model which incorporates the excluded volume effect in a thermodynamically consistent manner. We find that the new model works even for the cases of extremely large temperatures and densities where most of other approaches fail. Furthermore, the new expressions for thermodynamical variables resemble in form with those obtained from thermodynamically inconsistent models and thus a useful correction factor has been suggested here which converts inconsistent expressions into thermodynamically consistent ones. Finally we compare the predictions of new model with those obtained from various old models.