Measurement of theπ+e+ν branching ratio

Abstract
A new measurement of the π+e+ν branching ratio gives Rπeν=Γ(π→eν+π→eνγ)/Γ (π→μν+π→μνγ) =[1.2265±0.0034(stat)±0.0044(sys)]×104. This result is in agreement with standard model calculations and confirms the hypothesis of electron-muon universality at the 0.2% level.