Calculations of penguin diagrams in B decays

Abstract

We analyze the effects of the space-like penguin diagrams in two body B decays $B^{-}\to K^{-}{\bar{K}}^0$ and $B^{-}\to {\pi }^{-}{\bar{K}}^0$. Special attention is paid to the operator $Q_6$, whose contribution is large in the BSW model, but vanishes in the PQCD method in the approximation of neglecting the masses in the final states. Suppressions of the space-like penguin diagrams are found in the PQCD method, which implies that the contributions of the space-like penguins are small compared to those of the time-like penguins.

Comments: Latex, 14 pages, including 3 figures (Postscript)