Color-Singlet $ψ_Q$ Production at $e^+e^-$ Colliders

Abstract

We calculate in closed form the complete ${\mathcal O}(α_s^2)$ color-singlet differential cross section for $e^+e^- \to γ^* \to ψ_Q+X$ 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 $ψ_Q$ mass by more than an order of magnitude. We also discuss the color-singlet model's predictions for direct $J/ψ$ angular and energy distributions at CLEO.