  If the neutral component of weak-scale dark matter is accompanied by a
charged excitation separated by a mass gap of less than ~20 MeV, WIMPs can form
stable bound states with nuclei. We show that the recent progress in
experiments searching for neutrinoless double-beta decay sets the first direct
constraint on the exoergic reaction of WIMP-nucleus bound state formation. We
calculate the rate for such process in representative models and show that the
double-beta decay experiments provide unique sensitivity to a large fraction of
parameter space of the WIMP doublet model, complementary to constraints imposed
by cosmology and direct collider searches.

High Energy Physics - Phenomenology;High Energy Astrophysical Phenomena;High Energy Physics - Experiment;Nuclear Experiment