Dynamical symmetry breaking in Nambu-Jona-Lasinio model under the influence of external electromagnetic and gravitational fields

TL;DR

This paper studies how external electromagnetic and gravitational fields influence dynamical symmetry breaking in the Nambu-Jona-Lasinio model, revealing effects like magnetic catalysis and curvature-dependent chiral symmetry restoration.

Contribution

It provides a detailed analysis of phase transitions and symmetry breaking in the NJL model under external fields using the proper-time formalism and large-N expansion.

Findings

Magnetic catalysis occurs in curved spacetime.

Chiral symmetry is restored above a critical curvature.

External fields significantly affect phase transition behavior.

Abstract

Dynamical symmetry breaking is investigated for a four-fermion Nambu-Jona-Lasinio model in external electromagnetic and gravitational fields. An effective potential is calculated in the leading order of the large-N expansion using the proper-time Schwinger formalism. Phase transitions accompanying a chiral symmetry breaking in the Nambu-Jona-Lasinio model are studied in detail. A magnetic calalysis phenomenon is shown to exist in curved spacetime but it turns out to lose its universal character because the chiral symmetry is restored above some critical positive value of the spacetime curvature.