Baryogenesis above the Fermi scale
W. Buchmüller · arXiv (Cornell University) · 1998
In the standard model and most of its extensions the electroweak transition is too weak to affect the cosmological baryon asymmetry. Due to sphaleron processes baryogenesis in the high-temperature, symmetric phase of the standard model is closely related to neutrino properties. The experimental indications for very small neutrino masses from the solar and the atmospheric neutrino deficits favour a large scale of B-L breaking. For hierarchical neutrino masses, with B-L broken at the unification scale $Λ_{GUT} \sim 10^{16}$ GeV, the observed baryon asymmetry $n_B/s \sim 10^{-10}$ is naturally explained by the decay of heavy Majorana neutrinos. The corresponding baryogenesis temperature is $T_B \sim 10^{10}$ GeV. In supersymmetric models implications for the mass spectrum of superparticles can be derived. A consistent picture is obtained with the gravitino as LSP, which may be the dominant component of cold dark matter.