Particle-accelerator constraints on isotropic modifications of the speed of light

TL;DR

This paper uses particle accelerator data to set extremely tight constraints on possible isotropic deviations of the speed of light, significantly improving previous bounds and discussing future experimental prospects.

Contribution

It provides the most stringent laboratory bounds to date on isotropic modifications of the speed of light within the SME framework.

Findings

Limits on deviations are tightened by over three orders of magnitude.

Constraints are derived from LEP and Tevatron data on vacuum Cherenkov radiation and photon stability.

Potential for future improvements with terrestrial and astrophysical observations is analyzed.

Abstract

The absence of vacuum Cherenkov radiation for 104.5 GeV electrons and positrons at LEP combined with the observed stability of 300 GeV photons at the Tevatron constrains deviations of the speed of light relative to the maximal attainable speed of electrons. Within the Standard-Model Extension (SME), the limit $-5.8\times10^{-12} \leq \tilde{\kappa}_{\rm tr}-{4/3}c_e^{00} \leq 1.2\times10^{-11}$ is extracted, which sharpens previous bounds by more than 3 orders of magnitude. The potential for further refinements of this limit with terrestrial experiments and astrophysical observations is discussed.