Indirect Signatures of Gravitino Dark Matter

TL;DR

This paper explores gravitino dark matter in supersymmetric models with R-parity breaking, showing that decaying gravitinos could explain cosmic ray anomalies while fitting cosmological constraints.

Contribution

It introduces a scenario where gravitino dark matter decays produce observable cosmic ray signatures, aligning with experimental anomalies and cosmological data.

Findings

A 150 GeV gravitino with a lifetime of 10^26 seconds can explain gamma-ray and positron excesses.

The model is consistent with primordial element abundances and matter-antimatter asymmetry.

Decaying gravitinos provide a viable indirect detection signal for dark matter.

Abstract

Supersymmetric models provide very interesting scenarios to account for the dark matter of the Universe. In this talk we discuss scenarios with gravitino dark matter in R-parity breaking vacua, which not only reproduce very naturally the observed dark matter relic density, but also lead to a thermal history of the Universe consistent with the observed abundances of primordial elements and the observed matter-antimatter asymmetry. In this class of scenarios the dark matter gravitinos are no longer stable, but decay with very long lifetimes into Standard Model particles, thus opening the possibility of their indirect detection. We have computed the expected contribution from gravitino decay to the primary cosmic rays and we have found that a gravitino with a mass of 150 GeV and a lifetime of 10^26 s could simultaneously explain the EGRET anomaly in the extragalactic gamma-ray background and the HEAT excess in the positron fraction.