Strongly Interacting Matter Under Extreme Conditions

TL;DR

This paper enhances the Hadron Resonance Gas model by incorporating unequal hadron radii, Lorentz contraction, mean-field potentials, and magnetic field effects, significantly improving the understanding of thermodynamics in strongly interacting matter under extreme conditions.

Contribution

It introduces the Modified and Lorentz contracted EVHRG models, and explores magnetic field effects, providing a more comprehensive modeling of repulsive interactions in hadronic matter.

Findings

Unequal radii and Lorentz contraction significantly affect thermodynamic quantities.

Magnetic fields alter susceptibilities and thermodynamic properties notably.

Electric charge susceptibility is more sensitive to magnetic fields than baryon susceptibility.

Abstract

Different variants of the Hadron Resonance Gas model have been used to describe the hadronic phase of strongly interacting matter. HRG model is improved by including repulsive interaction through the inclusion of excluded volume in Excluded Volume Hadron Resonance Gas (EVHRG) model. Here, the EVHRG model is further improved by incorporating unequal radii of hadrons which has been named as Modified Excluded Volume Hadron Resonance Gas (MEVHRG) model and also by taking their Lorentz contraction in Lorentz contracted MEVHRG model, namely, LMEVHRG model. Another way of incorporating the repulsive interactions in the HRG model is through the introduction of a mean-field potential. This is done in the HRG mean-field (HRGMF) model where the single particle energies are modified by a density dependent term. Both the inclusion of unequal radii and the Lorentz contraction have significant effects on the thermodynamic quantities and susceptibilities of conserved charges. The centre of mass energy dependence of some thermodynamic quantities in presence of repulsive interaction has been studied. Our study clearly indicates that proper modelling of repulsive interaction among hadrons is very important to explain the thermodynamic quantities and susceptibilities of conserved charges. The effect of static magnetic field in HRG and EVHRG models by the means of Landau levels has also been investigated. The vacuum part of the pressure, in presence of magnetic field, has been properly renormalised. The magnetic field is found to effect the thermodynamic quantities and the susceptibilities significantly. The electric charge susceptibility is influenced more strongly by the magnetic field than the baryon susceptibility. The total magnetization of hadronic matter is found to be positive.