CHIRAL PHASE TRANSITION IN COVARIANT NONLOCAL NJL MODELS

I. J. GENERAL; D. GOMEZ DUMM; N. N. SCOCCOLA

Workshop; Quark Matter in Astro- and Particle Physics; 2000

The properties of the chiral phase transition at finite temperature and chemical potential areinvestigated within an nonlocal covariant extension of the Nambu-Jona-Lasinio model based ona separable quark-quark interaction. We consider two types of non-local regulator functions:a gaussian regulator and the instanton liquid model regulator. In the first case we study boththe situation in which the Minkowski quark propagator has poles at real energies and thecase where only complex poles appear. We find that for both regulators the behaviour of thephysical quantities as functions of T and µ is quite similar. In particular, for small values of Tthe chiral phase transition is always of first order and, for finite quark masses, at certain “endpoint” the transition turns into a smooth crossover. Predictions for the position of this pointare presented.