A robust excess in the cosmic-ray antiproton spectrum: Implications for annihilating dark matter

An excess of similar to 10-20 GeV cosmic-ray antiprotons has been identified in the spectrum reported by the AMS-02 Collaboration. The systematic uncertainties associated with this signal, however, have made it difficult to interpret these results. In this paper, we revisit the uncertainties associated with the time, charge and energy-dependent effects of solar modulation, the antiproton production cross section, and interstellar cosmic-ray propagation. After accounting for these uncertainties, we confirm the presence of a 4.7 sigma antiproton excess, consistent with that arising from a m(chi) approximate to 64-88 GeV dark matter particle annihilating to b (b) over bar with a cross section of sigma v similar or equal to (0.8-5.2) x 10(-26) cm(3)/s. If we allow for the stochastic acceleration of secondary antiprotons in supernova remnants, the data continue to favor a similar range of dark matter models (m(chi) approximate to 46-94 GeV, sigma v approximate to (0.7-3.8) x 10(-26) cm(3)/s) with a significance of 3.3 sigma. The same range of dark matter models that are favored to explain the antiproton excess can also accommodate the excess of GeV-scale gamma rays observed from the Galactic center.