New decay modes of gravitino dark matter

TL;DR

This paper investigates new three-body decay modes of gravitino dark matter in supersymmetric models with R-parity violation, revealing they often dominate over previously considered two-body decays and significantly impact detection prospects.

Contribution

It introduces and analyzes new three-body decay channels of gravitino dark matter, showing their importance over traditional two-body decay modes in supersymmetric scenarios.

Findings

Three-body decay modes often dominate over two-body decays.

Gravitino lifetime and branching ratios are significantly altered.

Implications for indirect detection of dark matter are substantial.

Abstract

We consider the three-body decays of gravitino dark matter in supersymmetric scenarios with bilinear R-parity violation. In particular, gravitino decays into lepton+W^* (lepton f\bar f') and \nu+Z^* (\nu f\bar f) are examined for gravitino masses below Mw. After computing the gravitino decay rates into these three-body final states and studying their dependence on supersymmetric parameters, we find that these new decay modes are often more important than the two-body decay, into a photon and a neutrino, considered in previous works. Consequently, the gravitino lifetime and its branching ratios are substantially modified, with important implications for the indirect detection of gravitino dark matter.