Phase diagram of Nambu–Jona-Lasinio model with dimensional regularization

Abstract

Regularization dependence of the Nambu--Jona-Lasinio model leaves room for improvement. To help in choosing a suitable regularization scheme, we investigate the phase diagram on the temperature-chemical potential plane in the Nambu--Jona-Lasinio model with the dimensional regularization. While the structure of the resulting diagram shows resemblance to the one in the frequently used cutoff regularization, some results of our study indicate a striking difference between these regularizations. Diagrams in the dimensional regularization always indicate the first-order phase transition at high chemical potential, while the first-order transition does not occur in the cutoff method for some parameter sets.