  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.
