On Baryogenesis and $n \bar n$-Oscillations

We study a simple model where color sextet scalars violate baryon number at tree level but do not give rise to proton decay. In particular, we include one light and two heavy sextets with $\Delta B=2$ baryon number violating interactions that induce neutron anti-neutron oscillations. This setup also suggests an intimate connection to the generation of the observed baryon asymmetry in the Universe via the out of equilibrium decay of the heavy sextet scalars at around $10^{14}$ GeV. The large $SU(3)$-color charges of the scalar fields involved in generating the baryon asymmetry motivate us to study potentially significant washout effects. We numerically solve a set of Boltzmann evolution equations and find restrictions on the available model parameters imposed by successful high scale baryogenesis. Combining our new numerical results for baryogenesis with $n\bar n$-oscillation predictions and collider limits on the light sextet, we identify parameter regions where this model can be probed by current and future experiments.