Impact of eight-quark interactions in chiral phase transitions I: Secondary magnetic catalysis

TL;DR

This paper investigates how multi-quark interactions in the NJL model affect the chiral phase transition under strong magnetic fields, revealing a phenomenon called secondary magnetic catalysis where the order parameter sharply increases.

Contribution

It introduces the effect of eight-quark interactions on magnetic catalysis in the NJL model, highlighting a new secondary catalysis phenomenon at high magnetic field strengths.

Findings

Multi-quark interactions cause a sharp increase in the order parameter.

Secondary magnetic catalysis occurs at magnetic fields around 10^{14} G/MeV^2.

The model extends understanding of magnetic effects in QCD-like theories.

Abstract

The influence of a constant magnetic field on the order parameter of the four-dimensional Nambu and Jona-Lasinio model extended by the 't Hooft six-quark term and eight-quark interactions is considered. It is shown that the multi-quark interactions cause the order parameter to increase sharply (secondary magnetic catalysis) with increasing strength of the field at the characteristic scale $H\sim 10^{14}\Lambda^2$ G/MeV^2.