Cosmic ray propagation and dark matter in light of the latest AMS-02 data

Abstract

The AMS-02 experiment is measuring the high energy charged cosmic rays with unprecedented accuracy. We explore the possibility of determining the cosmic-ray propagation models using the AMS-02 data $alone$. A global Bayesian analysis of the constraints on the cosmic-ray propagation models from the latest AMS-02 data on the Boron to Carbon nuclei flux ratio and proton flux is performed, with the assumption that the primary nucleon source is a broken power law in rigidity. The ratio of the diffusion coefficient $D_{0}$ to the diffusive halo height $Z_{h}$ is found to be determined with high accuracy $D_{0}/Z_{h}\simeq 2.00\pm0.07\text{cm}^{2}\text{s}^{-1}\text{kpc}^{-1}$. The best-fit value of the halo width is $Z_{h}\simeq 3.3$ kpc with uncertainty less than $50\$. As a consequence, the typical uncertainties in the positron fraction is within a factor of two, and that in the antiproton flux is within an order of magnitude. Both of them are significantly smaller than that from the analyses prior to AMS-02. Taking into account all the uncertainties and correlations in the propagation parameters we derive conservative upper limits on the cross sections for DM annihilating into various standard model final states from the current PAMELA antiproton data. We also investigate the reconstruction capability of the future AMS-02 antiproton data on the DM properties. The result shows that for DM particles lighter than 100 GeV and with typical thermal annihilation cross section, the cross section can be well reconstructed with uncertainties about a factor of two for the AMS-02 three-year data taking.