Goldstini as the decaying dark matter

TL;DR

This paper proposes a new supersymmetric dark matter decay scenario involving goldstini, which naturally have long lifetimes and can explain cosmic ray positron excesses through three-body decays with missing energy.

Contribution

It introduces a novel goldstini-based decay mechanism that allows for leptophilic dark matter and softer spectra, fitting cosmic ray data better than previous models.

Findings

Goldstini decay into three-body final states with missing energy.

The model can fit PAMELA positron excess and Fermi-LAT measurements.

Decays can be leptophilic and produce softer spectra.

Abstract

We consider a new scenario for supersymmetric decaying dark matter without R-parity violation in theories with goldstini, which arise if supersymmetry is broken independently by multiple sequestered sectors. The uneaten goldstino naturally has a long lifetime and decays into three-body final states including the gravitino, which escapes detection, and two visible particles. The goldstini low-energy effective interactions are derived, which can be non-universal and allow the dark matter to be leptophilic, in contrast to the case of a single sector supersymmetry breaking. In addition, the three-body decay with a missing particle gives a softer spectrum. Consequently, it is possible to fit both the positron excess observed by the PAMELA and the total e+ + e- measurements by the Fermi-LAT using universal couplings to all three lepton flavors or 100% branching fraction into electrons/positrons, both of which are disfavored in the conventional scenario of dark matter decays into two or four visible particles without missing energy.