1203.5925 (Zhi-Qing Zhang)

Annihilation Contribution to $B \to a_1(1260)(b_1(1235))K^*$ Decays    [PDF]

Zhi-Qing Zhang

Within the framework of perturbative QCD approach, we study the charmless two-body decays $B\to a_1(1260)K^*, b_1(1235)K^*$. Using the decays constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results: (a) Our predictions for the branching ratios are consistent well with the QCDF results within errors, but much larger than the naive factorization approach calculation values. BarBar has searched the decays $B\to a^-_1\bar K^{*0}, b_1K^*$ and set the upper limits for their branching ratios, which are (much) lower than our predictions. The current data seem to imply that penguin annihilation is small in these penguin-dominated decays. Certainly, if the factorizable annihilation diagram contributions are turned off, the branching ratios will fall dramatically and many of them reduced by more than half. It needs further accurate experiments to clarify the differences between the theoretical predictions and the present upper limits. (b) We predict that the similar anomalous polarizations occured in decays $B\to \phi K^*$ also happen in decays $B\to a_1K^*$, while not happen in decays $B\to b_1K^*$. Here still the contributions from the annihilation diagrams play an important role to explain the lager transverse polarizations in decays $B\to a_1K^*$, while are not sensitive to the polarizations in decays $B\to b_1K^*$. (c) Our predictions for the direct CP-asymmetries agree well with the QCDF results within errors. The decays $\bar B^0\to b^{+}_1K^{*-}, B^-\to b^{0}_1K^{*-}$ have larger direct CP-asymmetries, which could be measured by the present LHCb experiments.

View original: http://arxiv.org/abs/1203.5925