Measurement of the decay π+→e+νee+e− and search for a light Higgs boson

Abstract The radiative pion decay π + →e + ν e e + e − has been measured and values for the weak form factors F V , F A and R have been obtained. The measured branching ratio is Λ ( π + →e + ν e e + e − )/ Λ ( π + → μ + ν μ )=(3.2±0.5)×10 −9 . A light Higgs boson h with standard couplings to quarks is excluded in the mass range 10 MeV/ c 2 ⩽ m h ⩽110 MeV/ c 2 at 90% CL.