Power corrections in charmless B decays *

Power corrections seem to play an important role in charmless B decays as indicated by recent analysis using QCD Factorization. In this talk, I would like to report on a recent work on power corrections in charmless B decays. By using the ratio of the branching fraction of B+ → π+K*0 to that of B0 → π− ρ+, for which the theoretical uncertainties are greatly reduced, it is shown in a transparent manner that power corrections in charmless B decays are probably large and that the B0 → K− ρ+ decay could be explained with the annihilation term included. For ratios of direct CP asymmetries, QCD Factorisation with the annihilation terms included would predict the direct CP asymmetry of B → π+ π− to be about 3 times larger than that of B → π±K-+, with opposite sign. In particular, the large measured value for B → π±K-+, CP asymmetry implies naturally a corresponding large B → π+ π− CP asymmetry as observed by Belle. Experimentally any significant deviation from this prediction would suggest either new physics or possibly the importance of long-distance rescattering effects.