On the spontaneous breaking of Lorentz invariance

TL;DR

This paper explores potential Lorentz invariance violations through cosmic ray data and gamma-ray/neutrino timing, proposing new bounds and signatures for such fundamental symmetry breaking.

Contribution

It connects cosmic ray bounds with Lorentz violation parameters and suggests a novel energy-independent, chirality-dependent time delay signature in astrophysical signals.

Findings

Bounds on Lorentz violation from cosmic rays beyond GZK cut-off

Proposed energy-independent time delay signature in gamma-ray and neutrino signals

Dependence of time delay on particle chirality

Abstract

We show that estimates of the Lorentz symmetry violation extracted from ultra-high energy cosmic rays beyond the GZK cut-off set bounds on the parameters of a Lorentz-violating extension of the Standard Model. Moreover, we argue that correlated measurements of the difference in the arrival time of gamma-ray photons and neutrinos emitted from Active Galactic Nuclei or Gamma-Ray Bursts may provide a signature for a possible violation of the Lorentz symmetry. We find that this time delay is energy independent, but that it has a dependence on the chirality of the particles involved.