Competing mechanisms of chiral symmetry breaking in a generalized Gross-Neveu model

TL;DR

This paper analyzes a generalized 2D chiral Gross-Neveu model, revealing complex phenomena like spontaneous parity breaking, twisted baryons, and vacuum structures, through analytical methods in the leading derivative expansion.

Contribution

It introduces a generalized model with explicit chiral symmetry breaking and explores its rich vacuum and hadron spectrum analytically, uncovering new phenomena not seen in simpler models.

Findings

Spontaneous parity breaking occurs under certain parameters.

Presence of twisted kink-like baryons with vacuum angle dependence.

Crystalline phases with alternating baryons and false vacuum states.

Abstract

Chiral symmetry of the 2-dimensional chiral Gross-Neveu model is broken explicitly by a bare mass term as well as a splitting of scalar and pseudo-scalar coupling constants. The vacuum and light hadrons - mesons and baryons which become massless in the chiral limit - are explored analytically in leading order of the derivative expansion by means of a double sine-Gordon equation. Depending on the parameters, this model features new phenomena as compared to previously investigated 4-fermion models: spontaneous breaking of parity, a non-trivial chiral vacuum angle, twisted kink-like baryons whose baryon number reflects the vacuum angle, crystals with alternating baryons, and appearance of a false vacuum.