Testing the dark matter scenario in the inert doublet model by future precision measurements of the Higgs boson couplings

We evaluate radiative corrections to the Higgs boson couplings in the inert doublet model, in which the lightest component of the Z2 odd scalar doublet field can be a dark matter candidate. The one-loop contributions to the hVV, hff, and hhh couplings are calculated in the on-shell scheme, where h is the Higgs boson with the mass 125 GeV, V represents a weak gauge boson, and f is a fermion. We investigate how the one-loop corrected Higgs boson couplings can be deviated from the predictions in the standard model under the constraints from perturbative unitarity and vacuum stability in the scenario where the model can explain current dark matter data. When the mass of the dark matter is slightly above a half of the Higgs boson mass, it would be difficult to test the model by the direct search experiments for dark matter. We find that in such a case the model can be tested at future collider experiments by either the direct search of heavier inert particles or precision measurements of the Higgs boson couplings.