Cogenerating and Pre-annihilating Dark Matter by a New Gauge Interaction
  in a Unified Model
  Grand unified theories based on large groups (with rank greater or equal to 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, which then decay late into light stable dark matter
particles that inherit their asymmetry. It is shown that such decays can come
from d=5 operators that are Planck or GUT suppressed. We derive constraints on
such models and present a simple realization based on the group SU(7).
