Phase diagram of the three-dimensional NJL model

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 $μ$. 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 ($μ$,temperature) plane. We also discuss numerical results by Hands et al. which showed that the system is critical for $μ>μ_c$ and the diquark condensate is zero.