B-L violating proton decay and late cosmological baryon production

We analyze the consequences on matter stability of baryon violating interactions generating a cosmological baryon asymmetry at temperatures much below the grand unified mass. We show that in a class of models where weak couplings of nonordinary fermions to ordinary matter are used to achieve a late baryon production, nucleon decays are predicted to violate B - L, but to respect the ΔB = -ΔL selection rule. The analysis is conducted in an effective SU(3) x SU(2) x U(1) theory, with an illustration in SU(5). The mechanism could be relevant for cosmological baryon production in supersymmetric grand unified theories. (orig.)