keV Sterile Neutrino Dark Matter and Low Scale Leptogenesis

TL;DR

This paper proposes a minimal extension of the Standard Model that explains the 3.55 keV X-ray line, neutrino masses, and baryon asymmetry through low-scale leptogenesis and keV-scale sterile neutrino dark matter.

Contribution

It introduces a simple model linking keV sterile neutrino dark matter with low-scale leptogenesis and explains the X-ray line within a unified framework.

Findings

The model accounts for the 3.55 keV X-ray line via sterile neutrino decay.

It successfully generates baryon asymmetry through TeV-scale leptogenesis.

The keV sterile neutrino has a lifetime exceeding the age of the universe.

Abstract

We consider a simple extension of the Standard Model to consistently explain the observation of a peak in the galactic X-ray spectrum at 3.55 keV and the light neutrino masses along with the baryon asymmetry of the universe. The baryon asymmetry is generated through leptogenesis, the lepton asymmetry being generated by the decay of a heavy neutrino with TeV mass scale. The extra singlet fermion introduced in the model can be identified as a dark matter candidate of mass 7.1 keV. It decays with a lifetime much larger than the age of the universe, producing a final state photon. The Yukawa interactions between the extra singlet neutrino and a heavier right-handed neutrino play a crucial role in simultaneously achieving low scale leptogenesis and relic density of the keV dark matter candidate.