Phase diagram of the three-dimensional NJL model

TL;DR

This paper explores the phase diagram of the three-dimensional NJL model, revealing its critical behavior, universality class, and evidence for a tricritical point at finite temperature and chemical potential.

Contribution

It characterizes the critical properties and phase transitions of the NJL_3 model, including the universality class and the existence of a tricritical point.

Findings

Thermal transition belongs to the d=2 classical spin model universality class.

Evidence for a tricritical point in the (μ, temperature) plane.

System is critical for μ > μ_c with zero diquark condensate.

Abstract

With the exception of confinement the three-dimensional Nambu-Jona-Lasinio (NJL_3) model incorporates many of the essential properties of QCD. We discuss the critical properties of the model at nonzero temperature T and/or nonzero chemical potential $\mu$. We show that the universality class of the thermal transition is that of the d=2 classical spin model with the same symmetry. We provide evidence for the existence of a tricritical point in the ($\mu$,temperature) plane. We also discuss numerical results by Hands et al. which showed that the system is critical for $\mu>\mu_c$ and the diquark condensate is zero.