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

TL;DR

This paper reevaluates the color-singlet mechanism for inclusive J/ production in  decay, finding that QED contributions are significant and that previous models overestimate the production rate, highlighting gaps in understanding.

Contribution

It provides a revised calculation of J/ production in  decay, including both QCD and QED processes, showing the total rate is much lower than earlier predictions and experimental results.

Findings

QED process contribution is comparable to QCD process.

Total theoretical prediction is about an order of magnitude smaller than recent measurements.

Indicates the need for further theoretical and experimental investigation.

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.