Cosmic-Ray Signals from Dark Matter Annihilation into Scalars with Baryon Number

Abstract

Cosmic-ray antideuterons and antihelium-3 nuclei are promising probes of dark matter (DM). In light of potential detections of heavy antinuclei at AMS-02, we investigate a recently proposed scenario in which DM annihilates into color-singlet scalars carrying baryon and lepton number, which has been shown to enhance antideuteron and antihelium-3 fluxes relative to antiprotons. Accounting for Galactic propagation and detector sensitivities, we calculate the number of events predicted by our model for parameters that are compatible with the seven-year AMS-02 antiproton data. Broad regions of the DM-mediator mass plane result in observable antideuteron fluxes at AMS-02 and GAPS. While detecting antihelium-3 remains more challenging, potentially detectable fluxes can arise for light mediators and moderately light DM, and in general are enhanced relative to the standard WIMP predictions. Furthermore, we find antihelium-to-antideuteron event ratios of O(0.1), closer to those suggested by the reported AMS-02 candidate events than conventional WIMP predictions.