Muon decay: is it really non-neutrino physics?

Abstract

Muon decay, after more than 60 years of experimental and theoretical investigations, has been established as a firm basis for the standard model of electroweak interactions. The Lorentz structure of the decay interaction has been determined completely from existing experiments in a model-independent way. Neutrino experiments have played a decisive role in that analysis. Precision experiments in muon decay continue to be an important and sensitive testing ground for deviations from the standard model.