Simplified models with baryon number violation but no proton decay

We enumerate the simplest models that have baryon number violation at the classical level but do not give rise to proton decay. These models have scalar fields in two representations of SU(3)×SU(2)×U(1) and violate baryon number by two units. Some of the models give rise to nn̄ (neutron-antineutron) oscillations, while some also violate lepton number by two units. We discuss the range of scalar masses for which nn̄ oscillations are measurable in the next generation of experiments. We give a brief overview of the phenomenology of these models and then focus on one of them for a more quantitative discussion of nn̄ oscillations, the generation of the cosmological baryon number, the electric dipole moment of the neutron, and K⁰-K̄⁰ mixing.