  We analyze a simple extension of the Standard Model where the dark matter
particle is a Dirac fermion that is mixture of a singlet and an SU(2) doublet.
The model contains only four free parameters: the singlet and the doublet
masses and two new Yukawa couplings. Direct detection bounds in this model are
very strong and require the dark matter particle to be singlet-like. As a
result, its relic density has to be obtained via coannihilations with the
doublet. We find that the dark matter mass should be below 750 GeV, that the
singlet-doublet mass difference cannot exceed 9%, and that direct detection
experiments offer the best chance to probe this scenario. Finally, we also show
that this model can effectively arise in well-motivated extensions of the
Standard Model.
