The inert doublet model of dark matter revisited

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 and most appealing scenarios that can explain the dark matter. We show that, in this model, the annihilation of dark matter particles into three-body final states dominates, in a relevant portion of the viable 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 prospects for the direct and the indirect detection of inert higgs dark matter are significantly altered. In this letter, we derive the genuine viable parameter space of the inert doublet model, and we compute the correct direct detection cross section and annihilation branching ratios of inert higgs dark matter.