Finite-size effects on the phase diagram of difermion condensates in two-dimensional four-fermion interaction models

TL;DR

This paper studies how finite-size effects influence the phase diagram of chiral and difermion condensates in a two-dimensional four-fermion model, revealing size-dependent phase transitions at finite temperature and density.

Contribution

It introduces a method to incorporate finite-size effects using zeta-function and compactification techniques in the two-dimensional Nambu-Jona-Lasinio model, deriving size-dependent phase boundaries.

Findings

Finite-size effects shift phase transition lines.

Size-dependent critical lines are derived for different phases.

Boundary conditions influence the phase structure.

Abstract

We investigate finite-size effects on the phase structure of chiral and difermion condensates at finite temperature and density in the framework of the two-dimensional large-$N$ Nambu-Jona-Lasinio model. We take into account size-dependent effects by making use of $zeta$-function and compactification methods. The thermodynamic potential and the gap equations for the chiral and difermion condensed phases are then derived in the mean-field approximation. Size-dependent critical lines separating the different phases are obtained considering anti-periodic boundary conditions for the spatial coordinate.