mu->e Gamma decay versus mu->eee bound and lepton flavor violating processes in supernova

TL;DR

This paper investigates how lepton flavor violation in a See-Saw type II model affects supernova physics and predicts observable mu->e gamma decay rates within experimental reach, linking astrophysics with particle physics constraints.

Contribution

It identifies a specific LFV pattern consistent with experimental bounds that influences supernova dynamics and predicts testable mu->e gamma decay rates in upcoming experiments.

Findings

Predicted Br(mu->e gamma) between 0.5*10^(-12) and 6*10^(-12)

LFV processes can significantly modify supernova physics

Constraints on neutrino mixing and tau LFV decays

Abstract

Even tiny lepton flavor violation (LFV) due to some New Physics is able to alter the conditions inside a collapsing supernova core and probably to facilitate the explosion. LFV emerges naturally in a See-Saw type II model of neutrino mass generation. Experimentally LFV is constrained by rare lepton decay searches. In particular, strong bounds are imposed on the mu->eee branching ratio and on the mu-e conversion probability in muonic gold. Currently the mu->e gamma decay is under investigation in the MEG experiment which aims at dramatic increase of sensitivity in the next three years. We search for a See-Saw type II LFV pattern which fits all the experimental constraints, provides Br(mu->e gamma) not less than Br(mu->eee) and ensures a rate of LFV processes in supernova high enough to modify the supernova physics. These requirements are sufficient to eliminate almost all freedom in the model. In particular, they lead to a prediction 0.5*10^(-12) < Br(mu->e gamma)< 6*10^(-12), which is testable by MEG in the nearest future. The considered scenario also constrains neutrino mass-mixing pattern and provides lower and upper bounds on tau-lepton LFV decays. We also briefly discuss a model with a single bilepton in which the mu->eee decay is absent at the tree level.