WIMP Dark Matter from Gravitino Decays and Leptogenesis

TL;DR

This paper explores how heavy gravitino decays can produce WIMP dark matter and facilitate leptogenesis, linking neutrino masses with superparticle properties in a supersymmetric B-L breaking framework.

Contribution

It extends previous models to heavy gravitino scenarios, showing nonthermal WIMP production can explain dark matter while satisfying cosmological constraints.

Findings

Heavy gravitino decays can produce sufficient WIMP dark matter.

The model links neutrino masses with superparticle and gravitino masses.

Constraints from nucleosynthesis and leptogenesis are satisfied in certain parameter ranges.

Abstract

The spontaneous breaking of B-L symmetry naturally accounts for the small observed neutrino masses via the seesaw mechanism. We have recently shown that the cosmological realization of B-L breaking in a supersymmetric theory can successfully generate the initial conditions of the hot early universe, i.e. entropy, baryon asymmetry and dark matter, if the gravitino is the lightest superparticle (LSP). This implies relations between neutrino and superparticle masses. Here we extend our analysis to the case of very heavy gravitinos which are motivated by hints for the Higgs boson at the LHC. We find that the nonthermal production of 'pure' wino or higgsino LSPs, i.e. weakly interacting massive particles (WIMPs), in heavy gravitino decays can account for the observed amount of dark matter while simultaneously fulfilling the constraints imposed by primordial nucleosynthesis and leptogenesis within a range of LSP, gravitino and neutrino masses. For instance, a mass of the lightest neutrino of 0.05 eV would require a higgsino mass below 900 GeV and a gravitino mass of at least 10 TeV.