  Structure formation with cold dark matter (CDM) predicts halos with a central
density cusp, which are observationally disfavored. If CDM particles have an
annihilation cross section sigma*v ~ 10**(-29) (m/GeV) cm**2, then
annihilations will soften the cusps. We discuss plausible scenarios for
avoiding the early Universe annihilation catastrophe that could result from
such a large cross section. The predicted scaling of core density with halo
mass depends upon the velocity dependence of sigma*v, and s-wave annihilation
leads to a core density nearly independent of halo mass, which seems consistent
with observations.
