Anti-Deuterons and Anti-Helium Nuclei from Annihilating Dark Matter
  Recent studies of the cosmic-ray antiproton-to-proton ratio have identified
an excess of $\sim$10-20 GeV antiprotons relative to the predictions of
standard astrophysical models. Intriguingly, the properties of this excess are
consistent with the same range of dark matter models that can account for the
long-standing excess of $\gamma$-rays observed from the Galactic Center. Such
dark matter candidates can also produce significant fluxes of anti-deuterium
and anti-helium nuclei. Here we study the production and transport of such
particles, both from astrophysical processes as well as from dark matter
annihilation. Importantly, in the case of AMS-02, we find that Alfv\'{e}nic
reacceleration (i.e., diffusion in momentum space) can boost the expected
number of $\bar{\rm d}$ and ${}^{3}\overline{\textrm{He}}$ events from
annihilating dark matter by an order of magnitude or more. For relatively large
values of the Alfv\'{e}n speed, and for dark matter candidates that are capable
of producing the antiproton and $\gamma$-ray excesses, we expect annihilations
to produce a few anti-deuteron events and about one anti-helium event in six
years of AMS-02 data. This is particularly interesting in light of recent
reports from the AMS-02 Collaboration describing the detection of a number of
anti-helium candidate events.
