Antideuterons from Dark Matter Decay
  Recent observations of a large excess of cosmic-ray positrons at high
energies have raised a lot of interest in leptonic decay modes of dark matter
particles. Nevertheless, dark matter particles in the Milky Way halo could also
decay hadronically, producing not only a flux of antiprotons but also a flux of
antideuterons. We show that for certain choices of parameters the antideuteron
flux from dark matter decay can be much larger than the purely secondary flux
from spallation of cosmic rays on the interstellar medium, while the total
antiproton flux remains consistent with present observations. We show that if
the dark matter particle is sufficiently light, the antideuteron flux from dark
matter decay could even be within the reach of planned experiments such as
AMS-02 or GAPS. Furthermore, we discuss the prospects to observe the
antideuteron flux in the near future if the steep rise in the positron fraction
reported by the PAMELA collaboration is interpreted in terms of the decay of
dark matter particles.
