Color-Octet Quarkonium Production at the $Z$ Pole

Abstract

The direct production rate of $J/\psi$ via the color-octet mechanism is calculated at the $Z$ resonance. The color-octet production process $Z\to J/\psi q\bar{q}$ is shown to have a substantial branching ratio as well as a distinctive energy spectrum, which can be used as a powerful tool to distinguish from the color-singlet direct production of the $J/\psi$.

Comments: 9 pages in LaTeX and 2 figures. Some minor changes and also include the comparison with present data. It is the published version. Paper also available at http://www.ph.utexas.edu/~cheung/paper.html