Roads for Right-handed Neutrino Dark Matter: Fast Expansion, Standard Freeze-out, and Early Matter Domination

TL;DR

This paper explores a right-handed neutrino dark matter model with a new gauge interaction, analyzing its relic density, detection prospects, and parameter space under various cosmological scenarios.

Contribution

It introduces a novel right-handed neutrino dark matter model with gauge interactions and studies its relic density and detection in different cosmological contexts.

Findings

Relic density calculations for fast expansion, matter, and radiation domination.

Detection prospects include spin-independent and spin-dependent operators.

Parameter space viability for weak-scale right-handed neutrino dark matter.

Abstract

Right-handed neutrinos appear in several extensions beyond the Standard Model, specially in connection to neutrino masses. Motivated by this, we present a model of right-handed neutrino dark matter that interacts with Standard Model particles through a new gauge symmetry as well as via mass mixing between the new vector field and the Z boson, and investigate different production mechanisms. We derive the dark matter relic density when the Hubble rate is faster than usual, when dark matter decouples in a matter domination epoch, and when it decouples in a radiation domination regime, which is then followed by a matter domination era. The direct detection rate features a spin-independent but velocity suppressed operators, as well as a spin-dependent operator when the mass mixing is correctly accounted for. We put all these results into perspective with existing flavor physics, atomic parity violation, and collider bounds. Lastly, we outline the region of parameter space in which a weak scale right-handed neutrino dark matter stands as a viable dark matter candidate.