The (2+1)-dimensional Gross-Neveu model with a U(1) chiral symmetry at non-zero temperature

TL;DR

This paper investigates the phase structure of the (2+1)-dimensional Gross-Neveu model with U(1) symmetry at finite temperature, revealing two distinct symmetric phases and a pseudogap-like regime through numerical simulations.

Contribution

It provides the first numerical evidence of two separate chirally symmetric phases and a pseudogap regime in this model at non-zero temperature.

Findings

Identification of two different chirally symmetric phases separated by a BKT transition

Discovery of a pseudogap-like regime with fermion screening mass without chiral symmetry breaking

Numerical simulation results supporting the phase diagram of the model

Abstract

We present results from numerical simulations of the (2+1)-dimensional Gross-Neveu model with a U(1) chiral symmetry and N_f=4 fermion species at non-zero temperature. We provide evidence that there are two different chirally symmetric phases, one critical and one with finite correlation length, separated by a Berezinskii-Kosterlitz-Thouless transition. We have also identified a regime above the critical temperature in which the fermions acquire a screening mass even in the absence of chiral symmetry breaking, analogous to the pseudogap behaviour observed in cuprate superconductors.