M ar 1 99 5 Extended analysis of the ” penguin ” part of K → ππ amplitude

Extended analysis of the " penguin " part of K → ππ amplitude Abstract We make an attempt to clarify the role of the annihilation or " penguin " mode in the description of the K → ππ decay within the Standard Model. The attention is concentrated on new operators in the effective ∆S = 1 Hamiltonian and the violation of factorization for mesonic matrix elements of the local four-quark operators. We propose a regular method to evaluate the mesonic matrix elements of K → ππ transitions based on studying three-point correlators via QCD sum rules using the chiral effective theory as an underlying low-energy model for strong interaction. Matrix elements of the QCD penguin operator are calculated within this approach. The total " penguin " contribution is found to be relatively large that improves the theoretical description of the ∆I = 1/2 rule in non-leptonic kaon decays.