Constraints on dark matter annihilation from AMS-02 results

TL;DR

This paper uses AMS-02 cosmic ray data to set limits on dark matter annihilation, finding that the positron excess makes it challenging to attribute to dark matter unless assuming very conservative galactic models.

Contribution

It provides new constraints on dark matter annihilation cross sections based on recent cosmic ray measurements, highlighting the difficulty of explaining the positron excess with dark matter.

Findings

Limits on dark matter annihilation are weaker than gamma-ray constraints.

Explaining the positron excess with dark matter requires very high cross sections.

Conservative galactic models could allow for dark matter explanations of the excess.

Abstract

We use recently released data on the positron-to-electron ratio in cosmic rays from the AMS-02 experiment to constrain dark matter annihilation in the Milky Way. Due to the yet unexplained positron excess, limits are generally weaker than those obtained using other probes, especially gamma rays. This also means that explaining the positron excess in terms of dark matter annihilation is difficult. Only if very conservative assumptions on the dark matter distribution in the Galactic Center region are adopted, it may be possible to accommodate dark matter annihilating to leptons with a cross section above 10^-24 cm^3/sec. We comment on several theoretical mechanisms to explain such large annihilation cross sections.