Study of B0-->J/Psi D(*) and etac D(*) in Perturbative QCD

Abstract

Motivated by recent interest in soft $J/Ψ$ production in B decays, we investigate ${B}^0 \to J/ΨD^{(\star)}$ and $η_c D^{(\star)}$ decays in perturbative QCD. We find that, within that framework, these decays are calculable since the heavy $c\bar{c}$ pair in the final states is created by a hard gluon. The branching ratios are estimated to be around $10^{-7}\sim 10^{-8}$, too small to be consistent with the data, suggesting that other mechanism(s) contribute to the observed excess of soft $J/Ψ$ in ${B}^0 \to J/Ψ+ X$ decays. The possibility of the production of a hybrid $s{\bar d}g$ meson with mass about 2 GeV is briefly entertained.