The inert doublet model of dark matter revisited

TL;DR

This paper revisits the inert doublet model of dark matter, highlighting the significance of three-body annihilation processes which alter relic density calculations, detection prospects, and model viability.

Contribution

It introduces the impact of three-body annihilation modes into the inert doublet model, significantly affecting its phenomenology and viable parameter space.

Findings

Three-body annihilation dominates over two-body in certain parameter regions.

Relic density calculations are substantially modified by three-body processes.

Direct detection cross sections are up to two orders of magnitude smaller when including three-body annihilation.

Abstract

The inert doublet model, a minimal extension of the Standard Model by a second higgs doublet with no direct couplings to quarks or leptons, is one of the simplest scenarios that can explain the dark matter. In this paper, we study in detail the impact of dark matter annihilation into three-body final state on the phenomenology of the inert doublet model. We find that this new annihilation mode dominates, in a relevant portion of the parameter space, over those into two-body final states considered in previous analysis. As a result, the computation of the relic density is modified and the viable regions of the model are displaced. After obtaining the genuine viable regions for different sets of parameters, we compute the direct detection cross section of inert higgs dark matter and find it to be up to two orders of magnitude smaller than what is obtained for two-body final states only. Other implications of these results, including the modification to the decay width of the higgs and to the indirect detection signatures of inert higgs dark matter, are also briefly considered. We demonstrate, therefore, that the annihilation into three-body final state can not be neglected, as it has a important impact on the entire phenomenology of the inert doublet model.