B ->\eta_c K(\eta_c^\prime K) decays in QCD factorization
  We study the exclusive decays of $B$ meson into pseudoscalar charmonium states $\eta_c$ and $\eta_c^\prime$ within the QCD factorization approach and find that the nonfactorizable corrections to naive factorization are infrared safe at leading-twist order. The spectator interactions arising from the kaon twist-3 effects are formally power-suppressed but chirally and logarithmically enhanced. The theoretical decay rates are too small to accommodate the experimental data. On the other hand, we compare the theoretical calculations for $J/\psi, \psi^\prime$, and $\eta_c, \eta_c^\prime$, and find that the predicted relative decay rates of these four states are approximately compatible with experimental data. 
Zhongzhi Song, Ce Meng and Kuang-Ta Chao