Dark Matter Annihilation into Four-Body Final States and Implications for the AMS Antiproton Excess

TL;DR

This paper analyzes how dark matter annihilation into various final states, including four-body decays, can be constrained by astrophysical data and potentially explain the AMS antiproton excess.

Contribution

It provides updated constraints on dark matter annihilation cross sections for multiple final states using recent astrophysical data, and explores the possibility of explaining the AMS antiproton excess with light mediators.

Findings

Planck data strongly constrains light lepton final states.

Fermi-LAT data constrains four-body final states up to 10^4 GeV.

Dark matter with ~60-100 GeV mass and light mediators can explain AMS antiproton excess.

Abstract

We consider dark matter annihilation into a general set of final states of Standard Model particles, including two-body and four-body final states that result from the decay of intermediate states. For dark matter masses ~10-10^5 GeV, we use updated data from Planck and from high gamma-ray experiments such as Fermi-LAT, MAGIC, and VERITAS to constrain the annihilation cross section for each final state. The Planck constraints are the most stringent over the entire mass range for annihilation into light leptons, and the Fermi-LAT constraints are the most stringent for four-body final states up to masses ~10^4 GeV. We consider these constraints in light of the recent AMS antiproton results, and show that for light mediators it is possible to explain the AMS data with dark matter, and remain consistent with Fermi-LAT Inner Galaxy measurements, for m_\chi ~ 60-100 GeV mass dark matter and mediator masses m_\phi / m_\chi ~< 1.