2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/181703Belle has observed surprisingly copious production of $ψ(3770)$ in $B$ meson decay $B\to ψ(3770)K$, of which the rate is comparable to that of $B\to ψ(3686)K$. 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 $θ=-12^{\circ}$, 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.journal versionHigh Energy Physics - Phenomenologytext