Photon dispersion in causal sets

TL;DR

This paper presents a method to compute potential photon dispersion effects in a discrete space-time model called causal set theory, which could be observable in high-energy astrophysical phenomena.

Contribution

It introduces a novel application of the Feynman sum-over-histories formalism to causal set theory for calculating photon dispersion effects.

Findings

Method to estimate photon dispersion in causal sets

Potential observability in gamma-ray burst data

Framework for connecting quantum gravity models with astrophysical observations

Abstract

A very small dispersion in the speed of light may be observable in Fermi time- and energy-tagged data on variable sources, such as gamma-ray bursts (GRB) and active galactic nuclei (AGN). We describe a method to compute the size of this effect by applying the Feynman sum-over-histories formalism for relativistic quantum electrodynamics to a discrete model of space-time called \emph{causal set theory}.