An effective model for the QCD phase transitions at finite baryon density

TL;DR

This paper presents an effective quark-meson-nucleon model that describes QCD phase transitions at finite baryon density, predicting separated chiral and deconfinement transitions with specific density ranges.

Contribution

It introduces a unified framework with a bag field to model the transition between nucleon and quark degrees of freedom, highlighting the separation of chiral and deconfinement transitions.

Findings

Chiral transition occurs between 1.5 and 15.5 times nuclear saturation density.

Deconfinement transition occurs above 5 times nuclear saturation density.

Chiral and deconfinement transitions are always separated in the model.

Abstract

We introduce an effective quark-meson-nucleon model for the QCD phase transitions at finite baryon density. The nucleon and the quark degrees of freedom are described within a unified framework of a chiral linear sigma model. The deconfinement transition is modeled through a simple modification of the distribution functions of nucleons and quarks, where an additional auxiliary field, the bag field, is introduced. The bag field plays a key role in converting between the nucleon and the quark degrees of freedom. The model predicts that the chiral and the deconfinement phase transitions are always separated. Depending on the model parameters, the chiral transition occurs in the baryon density range of $(1.5-15.5)n_0$, while the deconfinement transition occurs above $5 n_0$, where $n_0$ is the saturation density.