Dark matter searches with cosmic antideuterons: status and perspectives
  The search for antideuterons in cosmic rays has been proposed as a promising
channel for dark matter indirect detection, especially for dark matter
particles with a low or intermediate mass. With the current operational phase
of the AMS-02 experiment and the ongoing development of a future dedicated
experiment, the General Antiparticle Spectrometer (GAPS), there are exciting
prospects for a dark matter detection in the near future. In this paper we
develop a detailed and complete re-analysis of the cosmic-ray antideuteron
signal, by discussing the main relevant issues related to antideuteron
production and propagation through the interstellar medium and the heliosphere.
In particular, we first critically revisit the coalescence mechanism for
antideuteron production in dark matter annihilation processes. Then, since
antideuteron searches have their best prospects of detection at low kinetic
energies where the effect of the solar wind and magnetic field are most
relevant, we address the impact of solar modulation modeling on the
antideuteron flux at the Earth by developing a full numerical 4D solution of
cosmic rays transport in the heliosphere. We finally use these improved
predictions to provide updated estimates of the reaching capabilities for
AMS-02 and GAPS, compatible with the current constraints imposed by the
antiprotons measurements of PAMELA. After the antiproton bound is applied,
prospects of detection of up to about 15 events in GAPS LDB+ and AMS-02
missions are found, depending on the dark matter mass, annihilation rate and
production channel from one side, and on the coalescence process, galactic and
solar transport parameters on the other.
