$\ell_1 \to \ell_2 \gamma$ in type III seesaw

TL;DR

This paper analyzes lepton flavor violating decays in the type III seesaw model, showing that observed rates would conflict with existing bounds unless other sources of violation are present.

Contribution

It provides a detailed calculation of decay rates in the type III seesaw model and discusses implications for experimental observations and additional sources of lepton flavor violation.

Findings

Observation of certain decays would contradict current bounds

Other sources of lepton flavor violation are implied

Constraints on the type III seesaw model parameters

Abstract

We study the decay rates of the $\mu \to e \gamma$ and $\tau \to \ell \gamma$ transitions in the framework of the type III seesaw model, where fermionic triplets are exchanged to generate neutrino masses. We show that the observation of one of those decays in planned experiments would contradict bounds arising from present experimental limits on the $\mu \to eee$ and $\tau \to 3 l$ decay rates, and therefore imply that there exist other sources of lepton flavour violation than those associated to triplet of fermions.