Quantum Gravitational Corrections to Electromagnetism And Backreaction

TL;DR

This paper explores how quantum gravity influences electromagnetism, deriving gauge-independent equations, new couplings, and analyzing effects on cosmological inflation and reheating.

Contribution

It introduces a gauge-independent quantum-corrected Maxwell's equation and a perturbative mechanism for a new scalar-electromagnetism coupling.

Findings

Quantum gravitational effects modify Maxwell's equations.

A new dimension six coupling between scalar and electromagnetism is proposed.

Photon-induced effective potential impacts inflation dynamics.

Abstract

This dissertation examines the impact of quantum gravity on electromagnetism and its backreaction, using perturbative general relativity as an effective field theory. Our analysis involves quantum-correcting Maxwell's equations to obtain a gauge-independent, real, and causal effective field equation that describes quantum gravitational effects on electromagnetism. Additionally, we present a perturbative mechanism through which quantum gravity induces a dimension six coupling between a massive scalar and electromagnetism. To investigate the effects of electromagnetism on the gravitational sector, we derive an exact, dimensionally regulated, Fourier mode sum for the Lorentz gauge propagator of a massive photon on an arbitrary cosmological background supported by a scalar inflaton. This allows us to calculate the effective potential induced by photons. Finally, we use a similar Fourier mode sum for a time-dependent mass to study the effective force on the inflaton 0-mode and its impact on reheating.