  The Higgs doublet can mediate a long-range interaction between multi-TeV
particles coupled to the Weak interactions of the Standard Model, while its
emission can lead to very rapid bound-state formation processes and
bound-to-bound transitions. Using the rates calculated in a companion paper,
here we compute the thermal decoupling of multi-TeV WIMP dark matter coupled to
the Higgs, and show that the formation of metastable dark matter bound states
via Higgs-doublet emission and their decay decrease the relic density very
significantly. This in turn implies that WIMP dark matter may be much heavier
than previously anticipated, or conversely that for a given mass, the dark
matter couplings to the Higgs may be much lower than previously predicted,
thereby altering the dark matter phenomenology. While we focus on a minimal
singlet-doublet model in the coannihilation regime, our calculations can be
extended to larger multiplets where the effects under consideration are
expected to be even more significant.
