Pion and muon decay

Abstract

The non-conservation of parity in pion and muon decay was discovered (Garwin, Lederman & Weinrich 1957; Friedman & Telegdi 1957) almost immediately after it had been observed in /?-decay. Experimentally it was shown that in the π - μ - e decay sequence the intensity of the final electrons had an angular distribution of the type I = A + B p μ ·p e´ where p μ (p e ) is the momentum of the muon (electron) at the point of emission. Since the muons were brought to rest between the two decay events, the connecting link could only be the muon spin. Equation (1) is thus the consequence of two separate equations, one for each decay process, pion decay σ μ = Cp μ, muon decay I = A + Dσ μ ·p e´