$\Delta L=2$ hyperon semileptonic decays

TL;DR

This paper calculates the rates of certain hyperon semileptonic decays involving Majorana neutrinos, finding they are below current experimental bounds and deriving a new limit on the neutrino's effective Majorana mass.

Contribution

It provides the first detailed calculation of hyperon decay rates involving Majorana neutrinos within a specific model, setting new bounds on neutrino properties.

Findings

Decay rates are below experimental bounds.

Derived an upper limit of 22 TeV on the effective Majorana neutrino mass.

Estimated background contributions for these decay channels.

Abstract

We compute the rates of semileptonic B_A \to B_Bl^-l^- (l=e or \mu) hyperon transitions in a model where intermediate states involve loops of baryons and a Majorana neutrino. These rates turn out to be well below present experimental bounds and other theoretical estimates. From the experimental upper limit on the \Xi^- \to p\mu^-\mu^- decay, we derive the bound <m_{\mu \mu}> < 22 TeV for the effective Majorana mass of the muon neutrino. Also, an estimate of background contributions for these decays due to the allowed B_A \to B_Bl^-l^-\bar{\nu}\bar{\nu} decays are provided.