A model for mixed warm and hot right-handed neutrino dark matter

TL;DR

This paper proposes a model where mixed warm and hot keV neutrino dark matter naturally arises, involving active and sterile neutrinos in an $SU(3)_L$ multiplet, with implications for cosmology and particle physics.

Contribution

It introduces a novel $SU(3)_L$-based model that explains the origin and abundance of mixed warm and hot keV neutrino dark matter.

Findings

The model prevents overproduction of keV neutrino dark matter.

It impacts Big Bang Nucleosynthesis predictions.

It affects the effective number of relativistic degrees of freedom.

Abstract

We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same $SU(3)_L$ multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom.