Cosmic-ray fermion decay through tau-antitau emission with Lorentz violation

TL;DR

This paper investigates how Lorentz and CPT violation in the tau-lepton sector can cause high-energy fermions to decay via tau-antitau emission, providing the first experimental bounds on this violation.

Contribution

It introduces the first experimental limit on Lorentz and CPT violation coefficients in the tau-lepton sector within the Standard-Model Extension framework.

Findings

High-energy fermions become unstable due to tau-antitau emission when Lorentz violation is present.

Calculated the fermion energy-loss rate caused by this decay process.

Established the first experimental bound on the Lorentz- and CPT-violating coefficient.

Abstract

We study CPT and Lorentz violation in the tau-lepton sector of the Standard Model in the context of the Standard-Model Extension, described by a coefficient which is thus far unbounded by experiment. We show that any non-zero value of this coefficient implies that, for sufficiently large energies, standard-model fermions become unstable against decay due to the emission of a pair of tau-antitau leptons. We calculate the induced fermion energy-loss rate and we deduce the first limit on the Lorentz- and CPT-violating coefficient.