Longevity Problem of Sterile Neutrino Dark Matter

TL;DR

This paper addresses the longevity problem of sterile neutrino dark matter by proposing a flavor symmetry that naturally extends the neutrino lifetime, aligning theoretical predictions with observational constraints.

Contribution

It introduces a flavor symmetry framework that naturally explains the extended lifetime of sterile neutrino dark matter, addressing the longevity problem.

Findings

Predicted X-ray fluxes are just below current observational bounds.

The flavor symmetry leads to a split mass spectrum for right-handed neutrinos.

The model naturally achieves the required longevity without fine-tuning.

Abstract

Sterile neutrino dark matter of mass O(1-10) keV decays into an active neutrino and an X-ray photon, and the non-observation of the corresponding X-ray line requires the sterile neutrino to be more long-lived than estimated based on the seesaw formula : the longevity problem. We show that, if one or more of the B-L Higgs fields are charged under a flavor symmetry (or discrete R symmetry), the split mass spectrum for the right-handed neutrinos as well as the required longevity is naturally realized. We provide several examples in which the predicted the X-ray flux is just below the current bound.