Lepton number violation in tau lepton decays

TL;DR

This paper reviews four-body lepton number violating tau decays, highlighting their potential to set stronger constraints on Majorana neutrino parameters than similar B meson decays.

Contribution

It introduces and analyzes four-body tau decay channels as a novel approach to constrain Majorana neutrino properties, surpassing previous methods.

Findings

Tau decay channels can provide stronger constraints on neutrino parameters.

Resonant Majorana neutrino exchange enhances these decay processes.

Comparison shows improved sensitivity over B meson decay analyses.

Abstract

Recent studies of novel four-body lepton number violating decays of $\tau$ leptons and neutral $B$ mesons are summarized and updated. These decays are assumed to be enhanced by the exchange of resonant Majorana neutrinos. It is shown that the $\tau^- \to \pi^+l^-l^-\nu_{\tau}$ decay channels, with $l=e$ or $\mu$, can provide stronger constraints on the mixing vs. mass parameter space of resonant Majorana neutrinos than analogous three-body decays of charged $B$ mesons.