Color-flavor dependence of the Nambu-Jona-Lasinio model and QCD phase diagram

Abstract

We study the dynamical chiral symmetry breaking/restoration for various numbers of light quarks flavors and colors using the Nambu-Jona-Lasinio (NJL) model of quarks in the Schwinger-Dyson equation framework, dressed with a color-flavor dependence of effective coupling. For fixed and varying , we observe that the dynamical chiral symmetry is broken when exceeds its critical value . For a fixed and varying , we observe that the dynamical chiral symmetry is restored when reaches its critical value . Strong interplay is observed between and , i.e., larger values of tend to strengthen the dynamical generated quark mass and quark-antiquark condensate, while higher values of suppress both parameters. We further sketch the quantum chromodynamics (QCD) phase diagram at a finite temperature T and quark chemical potential μ for various and . At finite T and μ, we observe that the critical number of colors is enhanced, whereas the critical number of flavors is suppressed as T and μ increase. Consequently, the critical temperature , , and co-ordinates of the critical endpoint in the QCD phase diagram are enhanced as increases and suppressed when increases. Our findings agree with the lattice QCD and Schwinger-Dyson equations predictions.