B - L violating nucleon decay and GUT scale baryogenesis in SO(10).

Minimal SO(10) models which utilize a 126-plet of Higgs for breaking B - L symmetry are predictive schemes for neutrino masses and mixings. These models have been known to predict sin22θ13≃0.09, which is consistent with recent measurements. It is shown that the same class of models generates naturally baryon number violating dimension seven operators leading to novel nucleon decay modes such as n→e-K+, e-π+ and p→νπ+ which violate B - L by two units. We find that in two-step breaking schemes of non-supersymmetric SO(10), the partial lifetimes for these modes can be within reach of experiments. The interactions responsible for these decay modes also provide a new way to understand the origin of matter in the universe via the decays of GUT scale colored scalar bosons. Their (B - L)-violating nature guarantees that the GUT scale induced baryon asymmetry is not washed out by the electroweak sphaleron interactions. In minimal SO(10) models this asymmetry is closely tied to the masses of quarks, leptons and the neutrinos. [ABSTRACT FROM AUTHOR]