Inclusive J/\psi Production In \Upsilon Decay Via Color-singlet Mechanism

Abstract

We reconsider the tree level color-singlet contribution for the inclusive J/\psi production in \Upsilon decay with the \alpha_{s}^{5} order QCD process \Upsilon\to J/\psi+c\bar{c}+g and \alpha^{2}\alpha_s^{2} order QED processes \Upsilon\to\gamma^{\ast}\to J/\psi+c\bar{c} and \Upsilon\to J/\psi+gg. It is found that the contribution of the QED process is compatible with that of the QCD process, and the numerical results for the QCD process alone is an order of magnitude smaller than the previous theoretical predictions, and our theoretical prediction in total is about an order of magnitude smaller than the recent CLEO measurement on the branching fraction B(\Upsilon\to J/\psi+X). It indicates that the J/\psi production mechanism in \Upsilon decay is not well understood, and further theoretical work and experimental analysis are still necessary.