Question of Lorentz invariance in muon decay

TL;DR

This paper explores how Lorentz invariance might be tested in muon decay by deriving direction-dependent decay rates and discussing experimental measurements to detect possible violations within the Standard Model Extension framework.

Contribution

It introduces a general Lorentz-violating modification to the muon decay rate and proposes experimental approaches to test Lorentz invariance in weak interactions.

Findings

Direction-dependent muon decay rates derived

Potential for detecting Lorentz violation in muon lifetime

Suggestions for experimental reanalyses and future tests

Abstract

Possibilities to test the Lorentz invariance of the weak interaction in muon decay are considered. We derive the direction-dependent muon-decay rate with a general Lorentz-violating addition to the W-boson propagator. We discuss measurements of the directional and boost dependence of the Michel parameters and of the muon lifetime as a function of absolute velocity. The total muon-decay rate in the Lorentz-violating Standard Model Extension is addressed. Suggestions are made for dedicated (re)analyses of the pertinent data and for future experiments.