Muon decay and neutrino mass

TL;DR

This paper calculates muon decay within V-A theory considering massive neutrinos, suggesting potential modifications to the Fermi constant and electron energy distributions without affecting polarization.

Contribution

It provides a theoretical analysis of muon decay accounting for neutrino masses, highlighting possible observable effects on decay parameters.

Findings

Possible modification of the Fermi constant due to neutrino masses

No impact on electron polarization in muon decay

Potential endpoint effects on electron energy and angle distributions

Abstract

The calculation of the $\mu$ decay is performed in V-A theory taking into account that, in agreement with the observation of the oscillations, the neutrinos must be massive. Provided that the masses of the electron and muon neutrinos are not higher than the known upper values, the result is a possible modification of the Fermi constant, no effect at all on the polarization of the outgoing electron and possibly an endpoint effect on the electron energy and angle distributions.