Flavor Goniometry by Proton Decay

Unification of strong and electroweak forces implies that protons (and bound neutrons) decay. Modes like νπ, e⁺π, and μ⁺K⁰ are expected, while modes like μ⁺π and e⁺K⁰ are "Cabibbo" suppressed. Branching ratios can reveal much about the nature of the unifying group and the origin of fermion masses. Plausible models of unification and flavor mixing give surprisingly different predictions for two-body branching ratios.