Baryogenesis via Gravitational Spontaneous Symmetry Breaking

We study baryogenesis in effective field theories where a U(1)(B-L)-charged scalar couples to gravity via curvature invariants. We analyze the general possibilities in such models, noting the relationships between some of them and existing models, such as Affleck-Dine baryogenesis. We then identify a novel mechanism in which U(1)(B-L) can be broken by couplings to the Gauss-Bonnet invariant during inflation and reheating. Using analytic methods, we demonstrate that this mechanism provides a new way to dynamically generate the net matter-antimatter asymmetry observed today and verify this numerically.