Radiative Decays of Cosmic Background Neutrinos in Extensions of MSSM with a Vector Like Lepton Generation

TL;DR

This paper investigates how extensions of the MSSM with a vector-like lepton generation can significantly reduce neutrino radiative decay lifetimes, making them potentially observable in future experiments, unlike in the Standard Model.

Contribution

It introduces a detailed analysis of neutrino decay lifetimes in MSSM extensions with vector-like leptons, highlighting the impact of CP phases and electric dipole moments.

Findings

Neutrino decay lifetimes can be as low as 10^{12}-10^{14} years in extended models.

Standard Model predicts neutrino lifetimes around 10^{43} years, beyond experimental reach.

Electric dipole moments often dominate the contributions to neutrino decay rates.

Abstract

An analysis of radiative decays of the neutrinos $\nu_j\to \nu_l \gamma$ is discussed in MSSM extensions with a vector like lepton generation. Specifically we compute neutrino decays arising from the exchange of charginos and charged sleptons where the photon is emitted by the charged particle in the loop. It is shown that while the lifetime of the neutrino decay in the Standard Model is $\sim 10^{43}$ yrs for a neutrino mass of 50 meV, the current lower limit from experiment from the analysis of the Cosmic Infrared Background is $\sim 10^{12}$ yrs and thus beyond the reach of experiment in the foreseeable future. However, in the extensions with a vector like lepton generation the lifetime for the decays can be as low as $\sim 10^{12}- 10^{14}$ yrs and thus within reach of future improved experiments. The effect of CP phases on the neutrino lifetime is also analyzed. It is shown that while both the magnetic and the electric transition dipole moments contribute to the neutrino lifetime, often the electric dipole moment dominates even for moderate size CP phases.