Tricritical behavior of the massive chiral Gross-Neveu model

TL;DR

This paper analyzes the phase diagram of the massive chiral Gross-Neveu model near the tricritical point, revealing complex phase transitions including both first and second order, contrasting with models having discrete chiral symmetry.

Contribution

It introduces a Ginzburg-Landau effective action approach to study the phase transitions in the model, highlighting the presence of a tricritical line and different transition orders.

Findings

Identification of first and second order phase transitions.

Presence of a tricritical line separating different phases.

Contrast with models having discrete chiral symmetry.

Abstract

The phase diagram of the massive chiral Gross-Neveu model (the 1+1-dimensional Nambu-Jona-Lasinio model at large N) is investigated in the vicinity of the tricritical point. Using the derivative expansion, the grand canonical potential is cast into the form of a Ginzburg-Landau effective action. Minimization of this action by variational and numerical methods reveals both 1st and 2nd order phase transitions to a chiral crystal phase, separated by a tricritical line. These findings are contrasted to the massive Gross-Neveu model with discrete chiral symmetry where only 2nd order transitions have been observed.