Fermion Singlet Dark Matter in a Pseudoscalar Dark Matter Portal

TL;DR

This paper investigates a minimal extension of the Standard Model with two gauge singlets, a fermion and a pseudoscalar, which can form a two-component dark matter system with viable relic abundance and detectable indirect signals.

Contribution

It introduces a simple two-singlet dark matter model with stable components and analyzes its relic abundance and experimental constraints, highlighting viable parameter regions.

Findings

Three viable parameter regions identified.

Model is sensitive to indirect detection experiments.

Dark matter relic abundance can be achieved without extra symmetries.

Abstract

We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the parameter space, and the model is sensitive to indirect searches.