Net-baryon number fluctuations in the Hybrid Quark-Meson-Nucleon model at finite density

TL;DR

This paper investigates how net-baryon number fluctuations behave at phase transitions in a hybrid model combining quark, meson, and nucleon dynamics, highlighting the impact of confinement on these fluctuations.

Contribution

It introduces a hybrid model with medium-dependent confinement effects to study net-baryon fluctuations at finite density and temperature.

Findings

Cumulants are significantly enhanced near the chiral transition.

Cumulants are less sensitive to the deconfinement transition.

The model predicts different types of phase transitions depending on scalar field expectations.

Abstract

We study the mean-field thermodynamics and the characteristics of the net-baryon number fluctuations at the phase boundaries for the chiral and deconfinement transitions in the Hybrid Quark-Meson-Nucleon model. The chiral dynamics is described in the linear sigma model, whereas the quark confinement is manipulated by a medium-dependent modification of the particle distribution functions, where an additional scalar field is introduced. At low temperature and finite baryon density, the model predicts a first-, second-order chiral phase transition, or a crossover, depending on the expectation value of the scalar field, and a first-order deconfinement phase transition. We focus on the influence of the confinement over higher-order cumulants of the net-baryon number density. We find that whereas the cumulants show a substantial enhancement around the chiral phase transition, they are not as sensitive to the deconfinement transition.