NJL with eight quark interactions: Chiral phases at finite T

TL;DR

This paper investigates how eight-quark interactions in a generalized NJL model influence chiral phase transitions at finite temperature, revealing new effects on transition temperature, nature, and sharpness not seen in simpler models.

Contribution

It introduces eight-quark interactions into the NJL model, demonstrating their essential role in stabilizing the potential and altering chiral transition characteristics at finite temperature.

Findings

Lowered the chiral transition temperature.

Sharpened the crossover temperature interval.

Enabled first order transitions with realistic quark masses.

Abstract

The thermodynamic potential and thermal dependence of low lying mass spectra of scalars and pseudoscalars are evaluated in a generalized Nambu -- Jona-Lasinio model, which incorporates eight-quark interactions. These are necessary to stabilize the scalar effective potential for the light and strange quark flavors, which would be otherwise unbounded from below. In addition it turns out that they are also crucial to i) lower the temperature of the chiral transition, in conformity with lattice calculations, ii) sharpen the temperature interval in which the crossover occurs, iii) or even allow for first order transitions to occur with realistic quark mass values, from certain critical values of the parameters. These are unprecedented results which cannot be obtained within the NJL approaches restricted to quartic and six-quark interactions.