Quantum Effects in Softly Broken Gauge Theories in Curved Space-Times

TL;DR

This paper investigates quantum effects in softly broken gauge theories within curved space-times, utilizing the Stueckelberg procedure to restore gauge symmetry and analyze specific models like Proca, massive QED, and torsion-fermion interactions.

Contribution

It applies the Stueckelberg scheme to perform quantum calculations in curved space-times for softly broken gauge theories, including detailed examples and qualitative analysis of spin-2 discontinuities.

Findings

Quantum effects depend on gauge fixing in curved space-times.

Explicit calculations for Proca, massive QED, and torsion-fermion models.

Discussion of discontinuity phenomena in massive spin-2 theories.

Abstract

The soft breaking of gauge or other symmetries is the typical Quantum Field Theory phenomenon. In many cases one can apply the St$\ddot{\rm u}$ckelberg procedure, which means introducing some additional field or fields and restore the gauge symmetry. The original softly broken theory corresponds to a particular choice of the gauge fixing condition. In this paper we use this scheme for performing quantum calculations for some softly broken gauge theories in an arbitrary curved space-time. The following examples are treated in details: Proca field, massive QED and massive torsion coupled to fermion. Furthermore we present a qualitative discussions of the discontinuity of quantum effects in the massive spin-2 field theory, paying special attention to the similarity and differences with the massless limit in the spin-1 case.