Critical end point in a thermo-magnetic nonlocal NJL model

Abstract

In this article we explore the critical end point in the $T-\mu$ phase diagram of a thermomagnetic nonlocal Nambu--Jona-Lasinio model in the weak field limit. We work with the Gaussian regulator, and find that a crossover takes place at $\mu ,B=0$. The crossover turns to a first order phase transition as the chemical potential or the magnetic field increase. The critical end point of the phase diagram occurs at a higher temperature and lower chemical potential as the magnetic field increases. This result is in accordance to similar findings in other effective models. We also find there is a critical magnetic field, for which a first order phase transition takes place even at $\mu =0$.

Comments: Some changes as well as new references have been added. Accepted for publication in International Journal of Modern Physics A