Phase Transitions in NJL and super-NJL models

TL;DR

This paper investigates phase transitions in 4D NJL and super-NJL models, revealing that non-supersymmetric models typically exhibit second-order transitions, while supersymmetric models can show both first and second-order transitions depending on parameters.

Contribution

It introduces an elementary method to determine the nature of phase transitions in NJL-type models, including supersymmetric versions, and characterizes their transition orders based on model parameters.

Findings

Non-susy NJL models usually have second-order phase transitions.

Weakly first-order transitions occur near fermion mass and cutoff scale.

Supersymmetric models can exhibit both first and second-order transitions depending on coupling and susy-breaking scale.

Abstract

An elementary method of determination of the character of the hot phase transition in 4d four-fermion NJL-type models is applied to non-supersymmetric and supersymmetric versions of simple NJL model. We find that in the non-susy case the transition is usually of the second order. It is weakly first order only in the region of parameters which correspond to fermion masses comparable to the cut-off. In the supersymmetric case both kinds of phase transitions are possible. For sufficiently strong coupling and sufficiently large susy-breaking scale the transition is always of the first order.