Cogenerating and pre-annihilating dark matter by a new gauge interaction in a unified model
Grand unified theories based on large groups (with rank ≥6) are a natural context for dark matter models. They contain Standard-Model-singlet fermions that could be dark matter candidates, and can contain new non-abelian interactions whose sphalerons convert baryons, leptons, and dark matter into each other, “cogenerating' a dark matter asymmetry comparable to the baryon asymmetry. In this paper it is shown that the same non-abelian interactions can “pre-annihilate' the symmetric component of heavy dark matter particles χ, which then decay late into light stable dark matter particles ζ that inherit their asymmetry. We derive cosmological constraints on the parameters of such models. The mass of χ must be <3000 TeV and their decays must happen when 2×10{sup −7}<T{sub dec}/m{sub χ}<10{sup −4}. It is shown that such decays can come from d=5 operators with coefficients of order 1/M{sub GUT} or 1/M{sub Pℓ}. We present a simple realization of our model based on the group SU(7).