Warm Dark Matter from keVins

TL;DR

This paper introduces a simple model for Warm Dark Matter involving keV inert fermions (keVins) produced thermally and diluted by decays of heavier GeV inert fermions (GeVins), applicable in various theoretical frameworks.

Contribution

It proposes a novel mechanism where keVins serve as WDM candidates, with their abundance controlled by entropy production from GeVins decays, within a broad class of models.

Findings

keVins can be thermally produced as WDM candidates

Entropy production from GeVins decays can dilute keVins abundance

Model applicable to E6-inspired supersymmetric and sterile neutrino models

Abstract

We propose a simple model for Warm Dark Matter (WDM) in which two fermions are added to the Standard Model: (quasi-) stable "keVins" (keV inert fermions) which account for WDM and their unstable brothers, the "GeVins" (GeV inert fermions), both of which carry zero electric charge and lepton number, and are (approximately) "inert", in the sense that their only interactions are via suppressed couplings to the Z. We consider scenarios in which stable keVins are thermally produced and their abundance is subsequently diluted by entropy production from the decays of the heavier unstable GeVins. This mechanism could be implemented in a wide variety of models, including E_6 inspired supersymmetric models or models involving sterile neutrinos.