Cerenkov-Like Emission of Pions by Photons in a Lorentz-Violating Theory

TL;DR

This paper investigates how Lorentz violation enables high-energy photons to emit pions via a Cerenkov-like process, and uses observational data to set stringent constraints on Lorentz-violating parameters.

Contribution

It introduces a novel mechanism for photon decay in Lorentz-violating theories and derives improved experimental bounds from astrophysical observations.

Findings

Photons up to 80 TeV are observed, constraining Lorentz violation.

The study sets a new limit on isotropic Lorentz-violating parameters at the $7\times 10^{-13}$ level.

Photon energy loss via pion emission is significant above certain thresholds.

Abstract

In the presence of Lorentz violation, the Cerenkov-like process $\gamma\rightarrow\gamma+\pi^{0}$ may become allowed for sufficiently energetic photons. Photons above the threshold would lose energy rapidly through pion emission. The fact that propagating photons with energies of up to 80 TeV survive to be observed on Earth allows us to place a one-sided constraint on an isotropic Lorentz violating parameter at the $7\times 10^{-13}$ level; this is more than an order of magnitude better than best previous result.