Inert-Sterile Neutrino: Cold or Warm Dark Matter Candidate

TL;DR

This paper proposes a variation of the inert doublet model where sterile neutrinos can serve as dark matter candidates that are either cold or warm, even with masses much larger than keV, and discusses their production, stability, and detection challenges.

Contribution

It introduces a novel inert doublet model variation allowing sterile neutrinos to be viable dark matter candidates beyond the keV range.

Findings

Sterile neutrinos can be cold or warm dark matter in this model.

Produced non-thermally, they are stable with very small Standard Model couplings.

Detection in dark matter searches is very challenging, but collider signatures may be possible.

Abstract

In usual particle models, sterile neutrinos can account for the dark matter of the Universe only if they have masses in the keV range and are warm dark matter. Stringent cosmological and astrophysical bounds, in particular imposed by X-ray observations, apply to them. We point out that in a particular variation of the inert doublet model, sterile neutrinos can account for the dark matter in the Universe and may be either cold or warm dark matter candidates, even for masses much larger than the keV range. These Inert-Sterile neutrinos, produced non-thermally in the early Universe, would be stable and have very small couplings to Standard Model particles, rendering very difficult their detection in either direct or indirect dark matter searches. They could be, in principle, revealed in colliders by discovering other particles in the model.