Cosmic-ray antimatter nuclei as a probe for dark matter

An excess in the cosmic-ray antiproton-to-proton ratio has been identified in energies of ∼10–20 GeV relative to the predictions of standard astrophysical models. 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. Relying on recent improvements in our understanding of the cosmic-ray propagation, we revisit the question of antimatter antiprotons. Also relying on recent measurements of the coalescence properties of anti-nuclei from the ALICE experiment, we make projections on the expected fluxes of anti-deuterium and anti-helium nuclei that dark matter candidates that explain the antiproton excess, can give. Our projections focus on the ongoing observations by the Alpha Magnetic Spectrometer (AMS-02) and the upcoming observations by the General Antiparticle Spectrometer (GAPS). We find that for large values of the Alfvén speed, and for dark matter candidates that are capable of producing the antiproton and gamma-ray excesses, we expect a detectable signal of cosmic-ray anti-deuteron and anti-helium events at AMS-02 and GAPS.