Dark Matter Search in Space: Combined Analysis of Cosmic Ray Antiproton-to-Proton Flux Ratio and Positron Flux Measured by AMS-02

Abstract

Dark matter search in space has been carried out for many years. Measurements of cosmic ray photons, charged antiparticles and neutrinos are useful tools for dark matter indirect search. The antiparticle energy spectra of cosmic rays have several exciting features such as the unexpected positron excess at energy about 10 -- 500 GeV and the remarkably flattening antiproton/proton at energy about 60--450 GeV precisely measured by the AMS-02 experiment, which can not be explained simultaneously by secondary production in interstellar medium. In this work, we report a combined analysis of cosmic ray antiproton and positron spectra arising from dark matter on the top of a secondary production in a spatial-dependent propagation model. We discuss the systematics from antiproton production cross section using the two latest Monte Carlo generators, i.e. EPOS LHC and QGSJET-II-04m, respectively. We compare their results. In the case of EPOS LHC, we find that the dark matter pair annihilating into tau leptons channel with 100% branching ratio is the only possible one channel scenario to explain data. On the other hand, there is not a single possible channel in the case of QGSJET-II-04m. We also propose possible two-channel scenarios based on these two Monte Carlo generators.