I : Chiral Perturbation for Kaons II: The $\Delta I=1/2$-rule in the Chiral Limit

Abstract

I : Chiral Perturbation Theory is introduced and its applications to semileptonic and nonleptonic kaon decays are discussed. II: The method of large $N_c$ is used to calculate $K\to\pi\pi$ nonleptonic matrix elements, in particular the matching procedure between long and short-distance evolution that takes all scheme dependence correctly into account is discussed. Numerical results reproduce the $\Delta I=1/2$ rule without the introduction of any free parameters.