Dark matter produced from right-handed neutrinos

TL;DR

This paper explores how dark matter can be produced via right-handed neutrinos, analyzing various scenarios and their observational implications within a generic framework and a specific type-I seesaw model extension.

Contribution

It provides a comprehensive systematic study of dark matter production mechanisms through right-handed neutrinos, covering multiple regimes and scenarios.

Findings

Multiple production scenarios depending on neutrino and dark sector masses.

Conditions under which dark matter can be in freeze-in or freeze-out regimes.

Potential observational signatures discussed.

Abstract

Right-handed neutrinos (RHNs) provide a natural portal to a dark sector accommodating dark matter (DM). In this work, we consider that the dark sector is connected to the standard model only via RHNs and ask how DM can be produced from RHNs. Our framework concentrates on a rather simple and generic interaction that couples RHNs to a pair of dark particles. Depending on whether RHNs are light or heavy in comparison to the dark sector and also on whether one or both of them are in the freeze-in/out regime, there are many distinct scenarios resulting in rather different results. We conduct a comprehensive and systematic study of all possible scenarios in this paper. For illustration, we apply our generic results to the type-I seesaw model with the dark sector extension, addressing whether and when DM in this model can be in the freeze-in or freeze-out regime. Some observational consequences in this framework are also discussed.