Leptogenesis after Chaotic Sneutrino Inflation and the Supersymmetry Breaking Scale

We discuss resonant leptogenesis arising from the decays of two nearly-degenerate right-handed neutrinos, identified as the inflaton and stabiliser superfields in a model of chaotic sneutrino inflation. We compare an analytical estimate of the baryon asymmetry $ \eta_B $ in the Boltzmann approximation to a numerical solution of the full density matrix equations, and find that the analytical result fails to capture the correct physics in certain regions of parameter space. The observed baryon asymmetry can be realised for a breaking of the mass degeneracy as small as $ \mathcal{O}(10^{-8}) $. The origin of such a small mass splitting is explained by considering supersymmetry (SUSY) breaking in supergravity, which requires a constant in the superpotential of the order of the gravitino mass $ m_{3/2} $ to cancel the cosmological constant. This yields additional terms in the (s)neutrino mass matrices, lifting the degeneracy and linking $ \eta_B $ to the SUSY breaking scale. We find that achieving the correct baryon asymmetry requires a gravitino mass $ m_{3/2} \geq \mathcal{O}(100) $ TeV.