A Robust Excess in the Cosmic-Ray Antiproton Spectrum: Implications for
  Annihilating Dark Matter
  An excess of $\sim$10-20 GeV cosmic-ray antiprotons has been identified in
the spectrum reported by the AMS-02 Collaboration. The systematic uncertainties
associated with this signal, however, have made it difficult to interpret these
results. In this paper, we revisit the uncertainties associated with the time,
charge and energy-dependent effects of solar modulation, the antiproton
production cross section, and interstellar cosmic-ray propagation. After
accounting for these uncertainties, we confirm the presence of a 4.7$\sigma$
antiproton excess, consistent with that arising from a $m_{\chi} \approx 64-88$
GeV dark matter particle annihilating to $b\bar{b}$ with a cross section of
$\sigma v \simeq (0.8-5.2) \times 10^{-26}$ cm$^{3}$/s. If we allow for the
stochastic acceleration of secondary antiprotons in supernova remnants, the
data continues to favor a similar range of dark matter models ($m_{\chi}\approx
46-94$ GeV, $\sigma v \approx (0.7-3.8)\times 10^{-26}$ 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.
