Gravitino dark matter in hybrid gauge-gravity models

TL;DR

This paper explores how hybrid gauge-gravity models can produce a gravitino dark matter candidate consistent with cosmological constraints, highlighting specific parameter regions with large tan(beta) and gauge mediation dominance.

Contribution

It demonstrates the viability of gravitino dark matter in hybrid supergravity models with high messenger scales, expanding the understanding of dark matter candidates in such frameworks.

Findings

Viable gravitino dark matter exists in certain parameter regions.

Large tan(beta) enhances the likelihood of gravitino being the LSP.

Gauge mediation dominance is crucial for consistent dark matter relic abundance.

Abstract

We study the phenomenology of generic supergravity models in which gravity mediation naturally competes with gauge mediation as the origin of supergravity-breaking. This class of hybrid models has been recently motivated in string inspired constructions and differs from usual gauge mediated supersymmetry breaking models in having messenger masses of order of the GUT scale. In these scenarios the gravitino can be the lightest supersymmetric particle in wide regions of the parameter space and therefore a potential candidate for dark matter. We investigate this possibility, imposing the WMAP bound on its relic abundance and taking into account constraints from Big Bang nucleosynthesis. We show that in these constructions viable gravitino dark matter can be obtained in specific regions of the parameter space, featuring large values of tan(beta) and where the supersymmetry breaking mechanism is dominated by gauge mediation.