The breakdown of parity conservation in the π-μ-e decay and a test of the two component neutrino theory

Abstract

6149 complete π-μ-e events have been measured in nuclear emulsion. 3021 events were in ordinary Ilford G5 emulsion and 3128 were in G5 emulsion containing twice the usual amount of gelatin relative to halide. The angular correlation between the initial directions of motion of μ-meson and electron, after possible edge effects have been eliminated, is of the form 1 - (0.149±0.033) cos θ in ordinary emulsion and 1 - (0.190±0.033) cos θ in diluted emulsion. This demonstrates conclusively the breakdown of parity conservation and charge conjugation in both steps of the π-μ-e process. It is shown that, with the aid of other data, the partial quenching of the μ-meson's initial spin orientation may be eliminated from these data and the true correlation of the fundamental process obtained: it is 1 - (0.283±0.060) cos θ. This asymmetry is consistent with the prediction of the two-component neutrino theory with