The ΔI=1/2 rule in non-mesonic weak decay of Λ-hypernuclei

By employing recent data on non-mesonic decay of s-shell Λ-hypernuclei we study, within the phenomenological model of Block and Dalitz, the validity of the ΔI=1/2 rule in the ΛN→NN process. Due to the low experimental precision, a possible violation of this rule can be neither proved nor excluded at present with sufficient accuracy: a pure ΔI=1/2 transition amplitude is excluded at 40% confidence level.