Effects of Lorentz invariance violation on cosmic ray photon emission and gamma ray decay processes

TL;DR

This paper investigates how Lorentz invariance violation (LIV) affects cosmic ray photon emission and gamma ray decay, revealing potential modifications to cosmic ray spectra and setting limits on LIV energy scales through high-energy photon observations.

Contribution

It introduces a generic LIV modification to particle dispersion relations and analyzes its impact on vacuum Cherenkov radiation and photon decay in cosmic rays.

Findings

LIV alters the emission rate depending on cosmic ray mass and charge.

LIV significantly increases photon decay into electron-positron pairs at high energies.

Constraints on LIV energy scale can be derived from gamma-ray observations.

Abstract

In this work, we use Lorentz invariance violation (LIV) introduced as a generic modification to particle dispersion relations to study some consequences of single photon emission, known as vacuum Cherenkov radiation, and photon decay processes in cosmic and gamma rays. These processes are forbidden in a Lorentz invariant theory but allowed under the hypothesis of LIV. We show that the emission rate have a dependency on the cosmic ray primary mass and the electric charge that could modify the UHECR spectrum. Furthermore, LIV dramatically enhances photon decay into an electro-positron pair above certain energy threshold. This last effect can then be used to set limits to the LIV energy scale from the direct observation of very high energy cosmic photon events by telescopes of gamma-rays.