Evidence for the leptonic neutral current reaction

In the Gargamelle neutrino experiment, three unambiguous candidates for the reaction ν μ + e − → ν μ e − have been observed corresponding to a cross section for a recoil electron energy within the range 0.3 e − GeV of 0.06 × 10 −41 E ν ( GeV ) cm 2 / electron . The calculated background is 0.44 ± 0.13 events and the probability that all three candidates could be due to this background is 1%.