On the Delta I=1/2 rule in the Lambda N -> NN reaction

It is shown that the mass dependence of the Lambda-lifetime in heavy hypern uclei is sensitive to the ratio of neutron-induced to proton-induced non-me sonic decay rates R-n/R-p. A comparison of the experimental mass dependence of the lifetimes with the calculated ones for different values of R-n/R-p leads to the conclusion that this ratio is larger than 2 on the confidence level of 0.75. This suggests that the phenomenological Delta I=1/2 rule mig ht be violated for the nonmesonic decay of the Lambda-hyperon.