Systematic Analysis of the Weak γ Decay of Hyperons

Abstract

The weak r decays of the hyperons are investigated systematically assuming SU (3) symmetry and the invariance of the weak vertex under the five transformations, U, R, RP, RU and RPU. Characteristic relations among the decay amplitudes, decay rates and the asymmetry parameters of various decay modes are obtained. ~ 1. Introduction In a recent experiment, Bazin et al. 1 l obtained the branching ratioby analysing the ranges of the proton emitted from the sigma produced by a K-beam stopped in the 30-in. Columbia-Brookhaven hydrogen bubble chamber. The experimental study of such rare decay modes of the hyperon will be quite interesting.The weak radiative decay of the J;+ hyperon has already been examined by many authors. 2 l Recently, Itoh has investigated the weak r decay of hyperons in the symmetry approach, assuming RP invariance of SU (3) and the pole approximation. 3 lThe purpose of this note is to investigate systematically the weak r decay of hyperons in the SU (3) limit on various models. Many people have pointed out the possibility of exploring the mechanism of the weak interaction by a phenomenological approach. According to them, a natural extenstion of the I .JJI = 1/2 rule for the nonleptonic decay would be to take the weak interactionHamiltonian as a member of an octet representaion of SU (3).Let us accept this principle and assume that the effective weak Hamiltonian is a member of an octet, and introduce furthermore the following specific hypotheses:1) The weak interaction is invariant under CP transformation, as well as under U, R, RP, RU and RPU transformations.