Cosmic rays from Leptonic Dark Matter

TL;DR

This paper proposes a leptonic dark matter decay model involving right-handed sneutrinos that predicts specific cosmic-ray signatures, including positron peaks and gamma-ray excesses, testable by upcoming observatories.

Contribution

It introduces a novel leptonic decay scenario for dark matter that explains cosmic-ray anomalies without producing excess antiprotons.

Findings

Predicts a sharp positron fraction peak.

Accounts for EGRET gamma-ray excess.

Suppresses primary antiproton flux.

Abstract

If dark matter possesses a lepton number, it is natural to expect the dark-matter annihilation and/or decay mainly produces the standard model leptons, while negligible amount of the antiproton is produced. To illustrate such a simple idea, we consider a scenario that a right-handed sneutrino dark matter decays into the standard model particles through tiny R-parity violating interactions. Interestingly enough, charged leptons as well as neutrinos are directly produced, and they can lead to a sharp peak in the predicted positron fraction. Moreover, the decay of the right-handed sneutrino also generates diffuse continuum gamma rays which may account for the excess observed by EGRET, while the primary antiproton flux can be suppressed. Those predictions on the cosmic-ray fluxes of the positrons, gamma rays and antiprotons will be tested by the PAMELA and FGST observatories.