A quasiparticle equation of state with a phenomenological critical point

TL;DR

This paper develops a hybrid quasiparticle model for the QCD equation of state that incorporates a phenomenological critical point, smoothly transitioning between hadronic and quark-gluon plasma phases, consistent with lattice data.

Contribution

It introduces a novel hybrid parameterization combining quasiparticle and hadronic models with a phenomenological critical point, ensuring thermodynamic consistency.

Findings

The model fits lattice QCD data at high temperature.

It describes a smooth crossover or first-order transition depending on chemical potential.

Thermodynamic consistency is maintained across phases.

Abstract

We propose a hybrid parameterization of a quasiparticle equation of state, where a critical point is implemented phenomenologically. In this approach, a quasiparticle model with finite chemical potential is used to describe the quark-gluon plasma phase by fitting to the lattice quantum chromodynamics data at high temperature. On the other hand, the hadronic resonance gas model with excluded volume correction is employed for the hadronic phase. An interpolation scheme is implemented so that the phase transition is a smooth crossover when the chemical potential is smaller than a critical value, or otherwise approximately of first order according to Ehrenfest's classification. Also, the thermodynamic consistency is guaranteed for the equation of state related to both the quasiparticle model and the implementation of the critical point.