Description of the first order phase transition region of an equation of state for QCD with a critical point

TL;DR

This paper maps the mean-field Ising model onto the QCD phase diagram to describe the first order phase transition region, including metastable states, aiding hydrodynamic simulations of heavy-ion collisions.

Contribution

It introduces a comprehensive equation of state for QCD with a critical point, encompassing the coexistence, metastable, and unstable phases, based on the Ising model mapping.

Findings

Reconstructed the full coexistence region in the QCD phase diagram.

Described thermodynamic behavior in the spinodal and metastable regions.

Compared the new equation of state with existing 3D-Ising model equations.

Abstract

We map the mean-field Ising model equation of state onto the QCD phase diagram, and reconstruct the full coexistence region in the case of a first order phase transition. Beyond the coexistence line, we maintain access to the spinodal region in the phase diagram, thus providing a description of metastable and unstable phases of matter as well. In this way, our approach includes the super-heated hadronic phase and the super-cooled quark-gluon plasma, which are useful for hydrodynamic simulations of the fireball created in a heavy-ion collision at low collision energy, where a first order phase transition is expected. We discuss the features of the pressure and other thermodynamic observables as functions of temperature and baryonic chemical potential, in particular their behavior in the coexistence region. Finally, we compare our equation of state to other 3D-Ising model ones available in the literature.