Dark matter annihilations and decays after the AMS-02 positron measurements

TL;DR

This paper uses AMS-02 positron flux data to set new limits on dark matter annihilation cross sections and lifetimes, providing constraints that are competitive with other methods especially for dark matter masses below 100 GeV.

Contribution

First to derive limits on dark matter properties using AMS-02 positron flux measurements, improving constraints on annihilation cross sections and lifetimes for various final states.

Findings

Strong limits on dark matter annihilation cross sections for masses below 100 GeV.

Constraints are competitive with those from positron fraction measurements.

Limits are particularly strong for annihilation into e+ e- and mu+ mu- channels.

Abstract

The AMS-02 collaboration has recently presented measurements of excellent quality of the cosmic electron and positron fluxes as well as the positron fraction. We use the measurements of the positron flux to derive, for the first time, limits on the dark matter annihilation cross section and lifetime for various final states. Working under the well-motivated assumption that a background positron flux exists from spallations of cosmic rays with the interstellar medium and from astrophysical sources, we find strong limits on the dark matter properties which are competitive, although slightly weaker, than those derived from the positron fraction. Specifically, for dark matter particles annihilating only into e+ e- or into mu+ mu-, our limits on the annihilation cross section are stronger than the thermal value when the dark matter mass is smaller than 100 GeV or 60 GeV, respectively.