Gravitational Contributions to the Running of Gauge Couplings

TL;DR

This paper investigates how gravity influences the evolution of gauge couplings by calculating gravitational corrections using a regularization scheme that preserves gauge symmetry, revealing nonzero effects contrary to earlier findings.

Contribution

It introduces a symmetry-preserving regularization method to accurately compute gravitational effects on gauge coupling running, challenging previous zero-result conclusions.

Findings

Gravitational corrections to the beta function are nonzero.

A regularization scheme preserving gauge symmetry is effective.

Results differ from earlier literature on gravitational effects.

Abstract

Gravitational contributions to the running of gauge couplings are calculated by using different regularization schemes. As the $\beta$ function concerns counter-terms of dimension four, only quadratic divergences from the gravitational contributions need to be investigated. A consistent result is obtained by using a symmetry-preserving loop regularization with string-mode regulators which can appropriately treat the quadratic divergences and preserve non-abelian gauge symmetry. The harmonic gauge condition for gravity is used in both diagrammatical and background field calculations, the resulting gravitational corrections to the $\beta$ function are found to be nonzero, which is different from previous results presented in the existing literatures.