Abstract
If dark matter particles are very heavy, they may form bound states mediated by the interaction with Standard Model particles. Direct detection experiments may be sensitive to break-up events. We propose to build an effective field theory in which dark matter particles are non-relativistic, and explore the possible existence of bound states, both in the case that the SU_L(2) x U_Y(1) symmetry is linearly realized and in the case that it is non-linearly realized (composite Higgs).