Final state interactions in Kaon decays Original Research Article

We quantify the important effect of strong final state interactions in the weak K→2π amplitudes, using the measured π–π phase shifts with J=0 and I=0,2. The main results of this analysis, with their implications for ε′/ε and the ΔI=1/2 rule, have been already presented in a previous paper [1]. Here we provide a detailed formal derivation of those results and further discuss the Standard Model prediction of ε′/ε.