High Energy Cosmic Rays from the Decay of Gravitino Dark Matter

TL;DR

This paper explores how decaying gravitino dark matter in supersymmetric models with R-parity violation can produce observable high-energy cosmic rays, potentially explaining excesses seen in gamma ray and positron data.

Contribution

It demonstrates that gravitino decay can account for observed cosmic ray excesses and calculates the resulting gamma ray and positron fluxes within this framework.

Findings

Gravitino decay can explain gamma ray excess observed by EGRET.

Positron excess can be attributed to gravitino decay as observed by HEAT.

Decay lifetime of gravitino can be longer than the universe's age despite R-parity violation.

Abstract

We study gamma ray and positron in high energy cosmic ray from the decay of the gravitino dark matter in the framework of supersymmetric model with R-parity violation. Even though R-parity is violated, the lifetime of the gravitino, which is assumed to be the lightest superparticle, can be longer than the present age of the universe if R-parity violating interactions are weak enough. In such a case, gravitino can be dark matter of the universe and its decay produces high energy cosmic rays. We calculate the fluxes of gamma ray and positron from the decay of the gravitino dark matter and discuss implications of such a scenario to present and future observations. In particular, we show that excesses of the fluxes of gamma ray and positron observed by EGRET and HEAT experiments, respectively, can be simultaneously explained as the cosmic rays from the decay of the gravitino dark matter.