Phenomenological description of quantum gravity inspired modified classical electrodynamics

TL;DR

This paper explores quantum gravity-inspired modifications to classical electrodynamics, modeling it as a dispersive, birefringent medium with non-local effects, analyzing causality and observational implications.

Contribution

It introduces a phenomenological framework incorporating quantum gravity corrections into electrodynamics using non-local constitutive relations up to second order.

Findings

Derivation of energy-momentum tensor and Green functions

Identification of frequency-dependent refraction indices

Demonstration that causality violations are suppressed in the radiation regime

Abstract

We discuss a large class of phenomenological models incorporating quantum gravity motivated corrections to electrodynamics. The framework is that of electrodynamics in a birefringent and dispersive medium with non-local constitutive relations, which are considered up to second order in the inverse of the energy characterizing the quantum gravity scale. The energy-momentum tensor, Green functions and frequency dependent refraction indices are obtained, leading to departures from standard physics. The effective character of the theory is also emphasized by introducing a frequency cutoff. The analysis of its effects upon the standard notion of causality is performed, showing that in the radiation regime the expected corrections get further suppressed by highly oscillating terms, thus forbiding causality violations to show up in the corresponding observational effects.