WIMP Dark Matter from Gravitino Decays and Leptogenesis
  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.
