Phase diagram of the three-dimensional NJL model

With the exception of confinement the three-dimensional Nambu-Jona-Lasinio (NJL₃) model incorporates many of the essential properties of QCD. We discuss the critical properties of the model at non-zero temperature T and/or non-zero chemical potential . 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 -plane. We also discuss numerical results by Handset al. which showed that the system is critical for and the diquark condensate is zero.Received: 30 September 2002, Published online: 22 October 2003PACS: 71.10.Fd Lattice fermion models (Hubbard model, etc.) - 05.70.Fh Phase transitions: general studies