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>μc​ and the diquark
condensate is zero.Comment: 3 pages, To appear in the proceedings of Conference on Quarks and
Nuclear Physics (QNP 2002), Julich, Germany, 9-14 Jun 200