# Has AMS-02 Observed Two-Component Dark Matter?

## TL;DR

This paper proposes that two distinct dark matter particles decaying into leptons can explain the AMS-02 cosmic-ray positron excess, fitting the observed spectral features with high accuracy.

## Contribution

It introduces a two-component dark matter model that fits AMS-02 positron data better than previous single-component models.

## Key findings

- Two dark matter species fit the positron excess data well
- The first species is 750 GeV decaying into tau leptons
- The second species is 2.3 TeV decaying into muons

## Abstract

There is convincing observational evidence for an increasing cosmic-ray positron-to-electron ratio at energies larger than $\sim 10$~GeV, at odds with expectations from secondary positron production. The most recent AMS-02 data exhibit an interesting spectral feature consisting of a bump at an energy around $300$~GeV followed by a drop around $\sim 800$~GeV. A possible explanation to the most recent data is that the excess positron originates from decaying dark matter. Here, we show that models consisting of two dark matter particle species contributing equally to the global cosmological dark matter density provide strikingly good fits to the data. The favored models, with a best-fit with $\chi^2/d.o.f \sim 0.5$ consist of a first species weighing $750$~GeV decaying with a lifetime $\tau_{\chi}\sim 10^{26}$~s to $\tau$ lepton pairs (or to a pair of vector bosons subsequently decaying to a $\tau$ pair each), and a second species with a mass around 2.3 TeV decaying to $\mu$ lepton pairs. We provide a few possible concrete realizations for this scenario.