Constraints on Lorentz violation from gravitational Cherenkov radiation

TL;DR

This paper uses cosmic-ray data to set new, stringent limits on Lorentz violation in gravity, significantly improving existing bounds and exploring future research directions involving gravitational and electromagnetic phenomena.

Contribution

It provides the first comprehensive constraints on nonminimal Lorentz-violating operators in gravity using gravitational Cherenkov radiation data.

Findings

Up to a billion-fold improvement on minimal operator limits.

First constraints on 74 nonminimal operators.

Two-sided constraints on 80 Lorentz-violating operators.

Abstract

Limits on gravitational Cherenkov radiation by cosmic rays are obtained and used to constrain coefficients for Lorentz violation in the gravity sector associated with operators of even mass dimensions, including orientation-dependent effects. We use existing data from cosmic-ray telescopes to obtain conservative two-sided constraints on 80 distinct Lorentz-violating operators of dimensions four, six, and eight, along with conservative one-sided constraints on three others. Existing limits on the nine minimal operators at dimension four are improved by factors of up to a billion, while 74 of our explicit limits represent stringent first constraints on nonminimal operators. Prospects are discussed for future analyses incorporating effects of Lorentz violation in the matter sector, the role of gravitational Cherenkov radiation by high-energy photons, data from gravitational-wave observatories, the tired-light effect, and electromagnetic Cherenkov radiation by gravitons.