The AMS-02 collaboration has recently reported the antiproton to proton ratio with improved accuracy. In view of uncertainties of the production and the propagation of the cosmic rays, the observed ratio is still consistent with the secondary astrophysical antiproton to proton ratio. However, it is nonetheless enticing to examine whether the observed spectrum can be explained by a strongly motivated dark matter, the wino dark matter. As we will show, the antiproton flux from the wino annihilation can explain the observed spectrum well for its mass range 2.5–3 TeV. The fit to data becomes particularly well compared to the case without the annihilation for the thermal wino dark matter case with a mass about 3 TeV. The ratio is predicted to decrease quickly at the energy several hundreds of GeV, which will be confirmed or ruled out in the near future when the AMS-02 experiment accumulates enough data at this higher energy region.

• Received 24 April 2015

DOI:https://doi.org/10.1103/PhysRevD.91.111701