Varieties of baryon and lepton nonconservation

The SU(3) × SU(2) × U(1) gauge symmetries are used to analyze the properties of various possible baryon- and lepton-nonconserving effective interactions among ordinary particles. A multiplicative quantum number is introduced as an aid in this analysis. Estimates are given of the masses of the exotic particles that could produce these effective interactions at observable levels. Cosmological and other considerations suggest that the effective interactions of exotic particles of any mass below ${10}^{14}$ GeV should conserve some linear combination $B+aL$ of baryon and lepton number.