Color-Singlet ${\psi }_Q$ Production at $e^{+}{e}^{-}$ Colliders

Abstract

We calculate in closed form the complete $\mathcal{O}({\alpha }_s^2)$ color-singlet differential cross section for $e^{+}{e}^{-}\to {\gamma }^{\ast }\to {\psi }_Q+X$ scattering. The cross section reduces at high energies to a heavy quark fragmentation form. We find that the energy scale at which the approximate fragmentation result becomes reliable exceeds the ${\psi }_Q$ mass by more than an order of magnitude. We also discuss the color-singlet model's predictions for direct $J/\psi$ angular and energy distributions at CLEO.

Comments: 17 pages RevTeX, 5 embedded ps/eps figures