Measurement of the Ratio of Axial-Vector to Vector Current in the DecayΣ−ne−→ν¯

Abstract

From approximately 550 ${\Sigma }^{-}$ electronic decays produced by stopping $K^{-}$ in liquid hydrogen we have selected a sample of 49 events in which the neutron from the ${\Sigma }^{-}$ leptonic decay is detected by a subsequent $n-p$ scatter. A maximum-likelihood analysis, including the effect of about 20% background, indicates that the magnitude of the ratio of the coupling constants is $\left|\frac{G_a}{G_V}\right|=0.23\mathrm{}\pm 0.16$, in excellent agreement with the prediction of the Cabibbo theory.