ELECTROWEAK PENGUIN EFFECTS BEYOND LEADING LOGARITHMS IN THE B-MESON DECAYS B--]K-PHI AND B--]PI-(K)BARO-ASTERISK

Using the low energy effective Hamiltonian for \DELTAB\=1, DELTAC=DELTAU=0 transitions, which has been calculated recently by Buras et al. beyond the leading logarithmic approximation, we analyze the penguin-induced B-meson decays B- --> K-PHI and B- --> pi-K0*BAR within the framework of the Bauer-Stech-Wirbel model and find, in contradiction to naive expectations, that the decay mode B- --> K K-PHI is affected strongly by electroweak penguin operators. These contributions depend on the value of the top-quark mass and reduce the branching ratio BR(B- --> K-PHI) by factors of 0.8...0.6 for m(t) = (130...250) GeV, respectively, relative to the results obtained by taking into account only QCD penguin operator contributions. On the other hand, we find that the effects of the electroweak penguins are very small for the transition B- --> pi-K0*BAR.