Lepton flavor conservation tests with muons

Massless neutrinos are assumed to account for the null branching ratios of lepton flavor nonconserving processes such as: (1) Rγ = μ → eγ/μ → decay; (2) Re = μ → eee/μ → decay; (3) R2 μ → eγγ/μ → decay; (4) R- = μ-Z → e-Z/μ-→ capture; (5) R+ = μ-Z → e+(Z-2)/μ → capture; (6) RL KL → μe/KL → decay; (7) RK = K+ → π+μe/K+ → decay. These low energy experiments, performed with ever greater sensitivity, are potential indicators of very high energy phenomena. The author reviews studies of reactions (1) - (5) and their impact on the extensions of the standard model. The observation of nonzero branching ratios in kaon experiments proposed or now running will require measurement of the other lepton flavor nonconserving reactions to unravel the correct theory. (L.L.) (25 refs., 3 tabs., 15 figs.)