Neutrino Experiment to Test the Nature of Muon-Number Conservation

This paper reports on a search for νₑ from μ⁺→e⁺νₑν_μ, allowed by multiplicative but not additive muon conservation, and for νₑ from μ⁺→e⁺νₑν_μ, allowed by both. Neutrinos from the Clinton P. Anderson Meson Physics Facility have been used, together with a six-ton Cherenkov counter filled with H₂O (D₂O) to look for νₑp→ne⁺(νₑd→ppe^-). The branching ratio ${({{μ}}⁺{→}{e}⁺{{ν}}ₑ{{ν}}_{{μ}})}{({{μ}}⁺{→}all)}={-}0.001±{}0.040$ is in excellent agreement with the additive law. The cross section $〈{σ}({{ν}}ₑd{→}pp{e}^{{-}})〉=(0.52±{}0.18)×{}{10}^{{-}40}$ ${cm}²$ agrees with theory.