A new viable region of the inert doublet model

Abstract

The inert doublet model, a minimal extension of the Standard Model by a\nsecond Higgs doublet, is one of the simplest and most attractive scenarios that\ncan explain the dark matter. In this paper, we demonstrate the existence of a\nnew viable region of the inert doublet model featuring dark matter masses\nbetween Mw and about 160 GeV. Along this previously overlooked region of the\nparameter space, the correct relic density is obtained thanks to cancellations\nbetween different diagrams contributing to dark matter annihilation into gauge\nbosons (W+W- and ZZ). First, we explain how these cancellations come about and\nshow several examples illustrating the effect of the parameters of the model on\nthe cancellations themselves and on the predicted relic density. Then, we\nperform a full scan of the new viable region and analyze it in detail by\nprojecting it onto several two-dimensional planes. Finally, the prospects for\nthe direct and the indirect detection of inert Higgs dark matter within this\nnew viable region are studied. We find that present direct detection bounds\nalready rule out a fraction of the new parameter space and that future direct\ndetection experiments, such as Xenon100, will easily probe the remaining part\nin its entirety.\n