Pion Decay and Possible Nonlocal Effects in the Theory of Fermi Interactions

Possible nonlocal effects in the theory of Fermi interactions are studied phenomenologically. Under certain simple assumptions, an effective Hamiltonian is derived which reduces to the local V-A interaction in the limit in which the momentum transfer between the two pairs of Fermi particles is very small. For larger values of the momentum transfer, corrective terms appear which may account phenomenologically for the deviations of the ρ value and the ratio R=(π→e+ν)(π→μ+ν) from the predictions of the local V-A theory. The pion and muon decays are analyzed in detail. Other weak processes are briefly discussed.