We analyze the decay BβΟK within the framework of QCD-improved
factorization. We found that although the twist-3 kaon distribution amplitude
dominates the spectator interactions, it will suppress the decay rates
slightly. The weak annihilation diagrams induced by (SβP)(S+P) penguin
operators, which are formally power-suppressed by order (Ξ/mbβ)2, are
chirally and logarithmically enhanced. Therefore, these annihilation
contributions are not subject to helicity suppression and can be sizable. The
predicted branching ratio of BββΟKβ is (3.8Β±0.6)Γ10β6 in
the absence of annihilation contributions and it becomes
(4.3β1.4+3.0β)Γ10β6 when annihilation effects are taken into
account. The prediction is consistent with CLEO and BaBar data but smaller than
the BELLE result.Comment: 13 pages, 3 figures. A major change for the presentation of
branching-ratio predictions. Experimental data are update