Fredrik Björkeroth
Speaker affiliation: 
University of Southampton
Tuesday, February 7, 2017 - 12:00
Seminar room (46/5081)
Leptogenesis after Sneutrino Inflation and the SUSY Breaking Scale

I will discuss resonant leptogenesis arising from the decays of two nearly-degenerate right-handed neutrinos, in a model of chaotic sneutrino inflation. I compare an analytical estimate of the baryon asymmetry of the universe (BAU) 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 O(10^-8). The origin of such a small mass splitting is explained by considering SUSY breaking in supergravity, which requires a constant in the superpotential of the order of the gravitino mass to cancel the cosmological constant. This yields additional terms in the (s)neutrino mass matrices, lifting the degeneracy and linking the BAU to the SUSY breaking scale. We find that achieving the correct BAU requires a gravitino mass of at least O(100) TeV.