We have studied charmless two-body B decays involving $\eta$ and $\eta'$ in the framework of QCD improved factorization appraoch. The spectator hard scattering mechanism for $\eta'$ production have been re-examined and extended, which contributions are incorporated consistently into the factorizable leading contributions. It is found that the conventional mechanism would give $Br(B\to \eta' K)\sim 30\times 10^{ -6}$ which agrees with predictions based on naive factorization approaches. With the incorporation of spectator hard scattering mechanism contributions, theoretical predictions are improved much and the bulk of $Br(B\to \eta' K)$ are accommodated in the reasonable parameter space. We have also presented calculations of $g^{ \ast}g^{ \ast}-\eta^{ (\prime)}$ transition form factors within the standard hard scattering approach. It is shown that the new contributions in the modes such as $B\to \eta' +vector$ and $B\to \eta+ \pi, \rho, K^{ (\ast)}$ are small. Direct CP-violation in those decay modes are predicted. It is shown that the prospects for measuring direct CP-violation effects in $B^{ \pm} \to$ $\eta' K^{ \pm}$, $\eta' \pi^{ \pm}$, $\eta \pi^{ \pm}$, and $\eta K^{ \pm}$ are promising at B factories in the near future.
Categories: hep-ph