A New Analysis of B_6^(1/2), B_8^(3/2), and the Delta I=1/2 Rule in the 1/N_c Expansion for K --> pi pi Decays

Abstract

We present a new calculation of long-distance contributions to the K --> pi pi amplitudes using the 1/N_c expansion within the framework of chiral perturbation theory. Along these lines we compute the chiral loop corrections to the operators Q_1, Q_2, Q_6, and Q_8. In the numerical analysis we present values for B_6^(1/2) and B_8^(3/2). We discuss also the implications for a theoretical understanding of the Delta I=1/2 selection rule.