Classification andJPGselection rules for weak currents

Four categories are defined of exotic and nonexotic first-class and second-class weak currents, three of which are suppressed in the standard model. Hadronic final states produced through various symmetry-breaking mechanisms are subject to selection rules which govern their allowed values of ${\mathrm{J}}^{\mathrm{PG}}$. We show that there are four types of suppressed transitions and give examples of each.