Decaying Dark Matter and the PAMELA Anomaly

TL;DR

This paper explores how decaying dark matter could explain the PAMELA positron excess, analyzing various decay channels and particles to match observed cosmic ray data.

Contribution

It provides a model-independent analysis of decaying dark matter scenarios, showing they can account for the PAMELA positron anomaly.

Findings

Decaying dark matter can explain the PAMELA positron excess.

Various decay channels are compatible with the observed data.

Both fermionic and scalar dark matter particles are considered.

Abstract

Astrophysical and cosmological observations do not require the dark matter particles to be absolutely stable. If they are indeed unstable, their decay into positrons might occur at a sufficiently large rate to allow the indirect detection of dark matter through an anomalous contribution to the cosmic positron flux. In this paper we discuss the implications of the excess in the positron fraction recently reported by the PAMELA collaboration for the scenario of decaying dark matter. To this end, we have performed a model-independent analysis of possible signatures by studying various decay channels in the case of both a fermionic and a scalar dark matter particle. We find that the steep rise in the positron fraction measured by PAMELA at energies larger than 10 GeV can naturally be accommodated in several realizations of the decaying dark matter scenario.