The Structure of the Weak Interaction $lambda$ + N $Yields$ N + N

Empirical evidence on the nonmesic decay of LAMBDA hypernuclei is analyzed in terms of the spin and isospin dependence of the weak interactions A + p yields n + p and LAMBDA + n yields n + n. The nonmesic decay rates for / sub LAMBDA /He/sup 4/ and /sub LAMBDA /H/sup 4/ were obtained by treating the A de-excitation by different nucleons as incoherent and assuming the validity of the DELTA I = 1/2 selection rule for these interactions. The ratios of nonmesic to pi /sup -/ decay modes and of the first reaction to the second were calculated as 1.68 plus or minus 0.36 and 0.5, respectively, for He/sup 6/ decay. The later ratio for H/sup 4/ was predicted to be 1/(8.8 plus or minus 3.2). Interpretation of the rates is discussed, and it is concluded that if the LAMBDA I = 1/2 rule holds for the LAMBDA -N yields N-N weak interaction and if present ideas about the current-current nature of weak interactions are valid, then the higher-order mesonic corrections to this primary four-fermion interaction must mask the simplicity of their primary form. (D.C.W.