The rare K decays and Z0 penguin contributions in the topcolor-assisted technicolor models
1 CCAST (World Laboratory), P.O. Box 8730, Beijing 100080,
2 Department of Physics, Peking University, Beijing 100871, P.R. China
3 Department of Physics, Henan Normal University, Xinxiang 453002, P.R. China
Received: 24 November 1998 / Revised version: 16 February 1999 /
Published online: 15 July 1999
We calculate the new contributions to the rare decays K, and from new Z0 penguin and box diagrams induced by the unit-charged scalars appearing in the topcolor-assisted technicolor (TC2) models. We find that: (a) the unit-charged top-pion and b-pion can provide large contributions to the rare K decays if they are relatively light; (b) the size of the mixing elements () is strongly constrained by the data of B0 meson mixing: for and GeV; (c) the enhancements to the branching ratios of rare K decays from new scalars can be as large as one order of magnitude; (d) there is a strong cancellation between the short- and the long-distance dispersive part of the decay , the constraint on the new short-distance part from this decay mode is thus not strong; (e) the typical TC2 model under study is generally consistent with the available rare K-decay data.