Combined analyses of the antiproton production from cosmic-ray interactions and its possible dark matter origin

Recent cosmic-ray (CR) studies have claimed the possibility of an excess on the antiproton flux over the predicted models at around 10 GeV, which can be the signature of dark matter annihilating into hadronic final states that subsequently form antiprotons. However, this excess is subject to many uncertainties related to the evaluation of the antiproton spectrum produced from spallation interactions of CRs. In this work, we implement a combined Markov-Chain Monte Carlo analysis of the secondary ratios of B, Be and Li and the antiproton-to-proton ratio ((p) over bar /p), while also including nuisance parameters to consider the uncertainties related to the spallation cross sections. This study allows us to constrain the Galactic halo height and the rest of propagation parameters, evaluate the impact of cross sections uncertainties in the determination of the antiproton spectrum and test the origin of the excess of antiprotons. In this way, we provide a set of propagation parameters and scale factors for renormalizing the cross sections parametrizations that allow us to reproduce all the ratios of B, Be, Li and (p) over bar simultaneously. We show that the energy dependence of the (p) over bar /p ratio is compatible with a pure secondary origin. In particular, we find that the energy dependence of the evaluated (p) over bar /p spectrum matches that observed from AMS-02 data at energies above similar to 3 GeV, although there is still a constant similar to 10% excess of (p) over bar over our prediction. We discuss that this discrepancy is more likely explained from a similar to 10% scaling in the cross sections of antiproton production, rather than a component of dark matter leading to antiprotons. In particular, we find that the bestfit WIMP mass (similar to 300 GeV) needed to explain the discrepancy lies above the constraints from most indirect searches of dark matter and the resultant fit is poorer than with a cross sections scaling.

Automated summary

Recent cosmic-ray studies have suggested a possible excess in the antiproton flux around 10 GeV, potentially related to dark matter, but with significant uncertainties. Through a Markov-Chain Monte Carlo analysis, researchers evaluated the origin of the excess and found a proton ratio matching AMS-02 data, with a remaining constant excess of around 10%.