Title: π+ Emission from hypernuclei and the weak ΔI = transitions
Abstract: Low energy π + emission in hypernuclear weak decays is studied in the soft pion limit.It is found that the π + decay amplitude is dominated by the ∆I = 3/2 part of nonmesonic weak decays according to the soft pion theorem.The ratios, R(π + /soft π -), for light hypernuclei are estimated in the direct quark mechanism, which predicts violation of the ∆I = 1/2 rule, and found to be about 1/3 for 4 Λ He.