%0 Journal Article
%T New Analysis of the Delta I = 1/2 Rule in Kaon Decays and the B_K Parameter
%A T. Hambye
%A G. O. Koehler
%A P. H. Soldan
%J Physics
%D 1999
%I arXiv
%R 10.1007/s100529900084
%X We present a new analysis of the Delta I = 1/2 rule in K --> pi pi decays and the B_K parameter. We use the 1/N_c expansion within the effective chiral lagrangian for pseudoscalar mesons and compute the hadronic matrix elements at leading and next-to-leading order in the chiral and the 1/N_c expansions. Numerically, our calculation reproduces the dominant Delta I = 1/2 K --> pi pi amplitude. Our result depends only moderately on the choice of the cutoff scale in the chiral loops. The Delta I = 3/2 amplitude emerges sufficiently suppressed but shows a significant dependence on the cutoff. The B_K parameter turns out to be smaller than the value previously obtained in the 1/N_c approach. It also shows a significant dependence on the choice of the cutoff scale. Our results indicate that corrections from higher order terms and/or higher resonances are large for the Delta I = 3/2 K --> pi pi amplitude and the (|Delta S| = 2) K^0 -- anti K^0 transition amplitude.
%U http://arxiv.org/abs/hep-ph/9902334v1