Higher-Order Corrections to Semileptonic Weak Processes

Using a strong formulation of lepton-hadron universality, higher-order corrections to semileptonic weak processes are related to the high-energy behavior of lepton-lepton weak-scattering amplitudes. The "weak cutoff" estimates of {~}4 GeV from the observed KL-KS mass difference and {~}16 GeV from the absence of the decay KL→μ⁺μ^- are interpreted as upper bounds on the center-of-mass energy at which cross sections for pure leptonic processes deviate significantly from the low-energy phenomenological predictions. A phenomenology for describing similar deviations in high-energy neutrino-nucleon reactions is developed. A sum rule relating such deviations is derived, as well as estimates of their order of magnitude using the parton model.