  We present a new mechanism for transferring a pre-existing lepton or baryon
asymmetry to a dark matter asymmetry that relies on mass mixing which is
dynamically induced in the early universe. Such mixing can succeed with only
generic scales and operators and can give rise to distinctive relationships
between the asymmetries in the two sectors. The mixing eliminates the need for
the type of additional higher-dimensional operators that are inherent to many
current asymmetric dark matter models. We consider several implementations of
this idea. In one model, mass mixing is temporarily induced during a two-stage
electroweak phase transition in a two Higgs doublet model. In the other class
of models, mass mixing is induced by large field vacuum expectation values at
high temperatures - either moduli fields or even more generic kinetic terms.
Mass mixing models of this type can readily accommodate asymmetric dark matter
masses ranging from 1 GeV to 100 TeV and expand the scope of possible
relationships between the dark and visible sectors in such models.
