Inflation and Leptogenesis in High-Scale Supersymmetry

International audienceNo-scale supergravity provides a successful framework for Starobinsky-like inflation models. Two classes of models can be distinguished depending on the identification of the inflaton with the volume modulus, T (C models), or a matterlike field, ϕ (WZ models). When supersymmetry is broken, the inflationary potential may be perturbed, placing restrictions on the form and scale of the supersymmetry breaking sector. We consider both types of inflationary models in the context of high-scale supersymmetry. We further distinguish between models in which the gravitino mass is below and above the inflationary scale. We examine the mass spectra of the inflationary sector. We also consider, in detail, mechanisms for leptogenesis for each model when a right-handed neutrino sector, used in the seesaw mechanism to generate neutrino masses, is employed. In the case of C models, reheating occurs via an inflaton decay to two Higgs bosons. However, there is a direct decay channel to the lightest right-handed neutrino which leads to nonthermal leptogenesis. In the case of WZ models, in order to achieve reheating, we associate the matterlike inflaton with one of the right-handed sneutrinos whose decay to the lightest right-handed neutrino simultaneously reheats the Universe and generates the baryon asymmetry through leptogenesis