Measurement of the pi→eν branching ratio

A measurement of the π→eν branching ratio using a NaI(Tl) spectrometer yields a value Γ((π→eν)+(π→eνγ))/Γ((π→μν)+(π→μνγ))=(1. 218±0.014)×${10}^{\mathrm{-}4}$. The result is consistent with expectations of the standard electroweak theory incorporating electron-muon universality.