Effects of a multi-quark interaction on color superconducting phase transition in an extended NJL model

Abstract

We study the interplay of the chiral and the color superconducting phase transition in an extended Nambu–Jona-Lasinio model with a multi-quark interaction that produces the nonlinear chiral–diquark coupling. We observe that this nonlinear coupling adds up coherently with the ω2 interaction to either produce the chiral–color superconductivity coexistence phase or cancel each other depending on its sign. We discuss that a large coexistence region in the phase diagram is consistent with the quark–diquark picture for the nucleon whereas its smallness is the prerequisite for the applicability of the Ginzburg–Landau approach.