Baryogenesis with Higher Dimension Operators

We propose a simple model of baryogenesis comprised of the standard model coupled to a singlet X via higher dimension operators O. In the early universe, X is thermalized by O mediated scattering processes before it decouples relativistically and evolves into a sizable fraction of the total energy density. Eventually, X decays via O in an out of equilibrium, baryon number and CP violating process that releases entropy and achieves baryogenesis for a broad range of parameters. The decay can also produce a primordial abundance of dark matter. Because X may be as light as a TeV, viable regions of parameter space lie within reach of experimental probes of neutron-antineutron oscillation, flavor physics, and proton decay.