Light Dark Matter from Leptogenesis

TL;DR

This paper proposes a leptogenesis-based model where sterile neutrino decays produce both baryon asymmetry and dark matter, allowing for light keV-scale dark matter with diverse thermal histories and potential indirect detection signals.

Contribution

It introduces a new non-thermal production mechanism for sterile neutrino dark matter within a two-sector leptogenesis framework, linking baryogenesis and dark matter genesis.

Findings

Accommodates keV-scale dark matter with hot, warm, or cold relics.

Predicts indirect detection signals, possibly explaining the 3.5 keV line.

Provides a novel non-thermal sterile neutrino production mechanism.

Abstract

We consider the implications of a shared production mechanism between the baryon asymmetry of the universe and the relic abundance of dark matter, that does not result in matching asymmetries. We present a simple model within a two sector leptogenesis framework, in which right handed sterile neutrinos decay out of equilibrium to both the Standard Model and the dark sector, generating an asymmetry in one and populating the other. This realization naturally accommodates light dark matter in the keV mass scale and above. Interactions in the dark sector may or may not cause the sector to thermalize, leading to interesting phenomenological implications, including hot, warm or cold thermal relic dark matter, while evading cosmological constraints. Under minimal assumptions the model provides a novel non-thermal production mechanism for sterile neutrino dark matter and predicts indirect detection signatures which may address the unexplained 3.5 keV line observed in various galaxy clusters.