Parity of the Neutral Pion and the Decayπ0→2e++2e−

Abstract

Two hundred and six electronic decays of the ${\pi }^0$, ${\pi }^0\to e^{+}+e^{-}+e^{+}+e^{-}$, have been observed in a hydrogen bubble chamber. The decay distributions of the electron pairs and the total rate for this process are shown to be in good agreement with theory. An examination of correlations of the $e^{+}{e}^{-}$ pair decay planes on the basis of electrodynamic predictions is in agreement with the hypothesis that the ${\pi }^0$ is pseudoscalar, but disagrees for scalar pions by 3.6 standard deviations.