Leptogenesis from loop effects in curved spacetime: baryon asymmetry without decays

by Jamie McDonald (Swansea University)

Thursday 3 Nov 2016, 14:00 → 15:00 Europe/London

OC208 (IPPP)

Explaining the matter-antimatter asymmetry of the Universe remains one of the most intriguing problems in particle physics and cosmology. A popular class of theories attributes this asymmetry to CP-violating decays of heavy particles in the Early Universe. We uncover a new gravitational source of baryogenesis within these models and show how the same Yukawa phases which provide the CP-violation for decays, combined with curved-spacetime loop effects, allow matter and antimatter to propagate differently in the presence of gravity. This splits the energy spectrum for matter and antimatter, leading to an asymmetric state driven by the expansion of spacetime geometry itself. By analysing the full Boltzmann equation, we demonstrate regions of parameter space where the asymmetry is produced solely by gravity, with decays playing no part at all.