Baryogenesis with higher dimension operators

Abstract

We propose a simple model of baryogenesis comprised of the standard model coupled to a singlet $X$ via higher dimension operators $\mathcal{O}$. In the early universe, $X$ is thermalized by $\mathcal{O}$ mediated scattering processes before it decouples relativistically and evolves into a sizable fraction of the total energy density. Eventually, $X$ decays via $\mathcal{O}$ 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 $n\mathrm{\text{\ensuremath{-}}}\overline{n}$ oscillation, flavor physics, and proton decay.