Sterile Neutrino portal to Dark Matter II: Exact Dark symmetry

TL;DR

This paper explores a minimal extension of the Standard Model with a dark sector and sterile neutrinos, analyzing how dark matter relic abundance and detection prospects are influenced by interactions mediated through sterile neutrinos.

Contribution

It introduces a novel dark sector model with sterile neutrinos mediating interactions, providing an alternative to Higgs portal scenarios for dark matter.

Findings

Dark matter relic abundance can be explained via annihilation into sterile neutrinos.

Scalar dark matter offers an alternative to Higgs portal models.

Constraints from direct detection and prospects for indirect detection are analyzed.

Abstract

We analyze a simple extension of the Standard Model (SM) with a dark sector composed of a scalar and a fermion, both singlets under the SM gauge group but charged under a dark sector symmetry group. Sterile neutrinos, which are singlets under both groups, mediate the interactions between the dark sector and the SM particles, and generate masses for the active neutrinos via the seesaw mechanism. We explore the parameter space region where the observed Dark Matter relic abundance is determined by the annihilation into sterile neutrinos, both for fermion and scalar Dark Matter particles. The scalar Dark Matter case provides an interesting alternative to the usual Higgs portal scenario. We also study the constraints from direct Dark Matter searches and the prospects for indirect detection via sterile neutrino decays to leptons, which may be able to rule out Dark Matter masses below and around 100 GeV.