Investigation of the phase diagram and bulk thermodynamic properties using the Polyakov–Nambu–Jona-Lasinio model with eight-quark interactions

Abstract

We present the bulk thermodynamic properties and phase diagram of strongly interacting matter in an extension of the 3-flavor Nambu--Jona-Lasinio (NJL) and Polyakov--Nambu--Jona-Lasinio (PNJL) models of QCD. Using a three-momentum cutoff scheme, we have extended the multiquark interaction terms up to eight order so that the stability of the vacuum is ensured in these models. We explore the effects of various combinations of the two eight-quark couplings ${g}_{1}$ and ${g}_{2}$ and present a comparative study between the NJL and PNJL models as well as lattice QCD data. The main effect of the eight-quark interaction term is to shift the critical end point in the $T\ensuremath{-}\ensuremath{\mu}$ phase diagram to a lower value of $\ensuremath{\mu}$ and a higher value of $T$, thus bringing them closer to lattice QCD results.