Spin polarization and color superconductivity in the Nambu--Jona-Lasinio model at finite temperature

TL;DR

This paper explores the coexistence and phase transitions of spin polarization and color superconductivity in the Nambu--Jona-Lasinio model at finite temperature and density, revealing complex phase structures.

Contribution

It introduces a tensor-type interaction into the NJL model and analyzes the resulting phase diagram, highlighting the conditions for coexistence of spin polarization and color superconductivity.

Findings

Chiral condensed phase exists at low temperature and chemical potential.

Color superconducting phase appears at intermediate chemical potential.

Coexistence of spin polarization and color superconductivity occurs at large chemical potential and low temperature.

Abstract

We investigate the possible existence of spin polarization and color superconductivity in the Nambu--Jona-Lasinio model with a tensor-type interaction at finite density and temperature. The thermodynamic potential is calculated by the functional integral method. Numerical results indicate that at low temperature and quark chemical potential the chiral condensed phase exists, and at intermediate chemical potential the color superconducting phase appears. In addition, depending on the magnitude of the tensor coupling, at large chemical potential and low temperature, a color superconducting phase and a spin polarized phase may coexist while at intermediate temperatures only the spin polarized phase occurs.