$\psi (3770)$ and $B$ meson exclusive decay $B\to \psi (3770)K$ in QCD factorization

Abstract

Belle has observed surprisingly copious production of $\psi (3770)$ in $B$ meson decay $B\to \psi (3770)K$, of which the rate is comparable to that of $B\to \psi (3686)K$. We study this puzzling process in the QCD factorization approach with the effect of S-D mixing considered. We find that the soft scattering effects in the spectator interactions play an essential role. With a proper parametrization for the higher twist soft end-point singularities associated with kaon, and with the S-D mixing angle $\theta =-12^{\circ }$, the calculated decay rates can be close to the data. Implications of these soft spectator effects to other charmonium production in $B$ exclusive decays are also emphasized.

Comments: journal version