Meson-cloud contributions in K->pi weak transitions

Contributions of low-energy ''eye'' and ''figure-eight'' quark diagrams to the K-->pi weak transitions are studied in a hadron-level phenomenological approach in which they originate from meson-cloud effects. If contributions from cloud mesons exhibit SU(6) symmetry, only the ''eye'' (low-energy penguin) diagram is nonvanishing. When the symmetry between contributions from intermediate pseudoscalar and vector mesons is broken, the Delta I=1/2(Delta I=3/2) amplitudes are enhanced (suppressed). The overall long-distance-induced enhancement of the ratio of the Delta I=1/2 amplitudes over the Delta I=3/2amplitudes is estimated at around 2.