Inelastic photoproduction ofJψandϒby gluons

Abstract

Amplitudes are derived for the quantum-chromodynamic subprocess $\gamma g\to \left(\frac{J}{\psi }\right)g$, with a specific wave function used to represent the $\frac{J}{\psi }$ as a $c\overline{c}$ system. The results are used to obtain the normalized total cross section ${\sigma }_{\gamma }$ for the inelastic process $\gamma N\to \left(\frac{J}{\psi }\right)X$, predictions for the $z$ and $p_T$ dependence of inelastic $\frac{J}{\psi }$ photoproduction, and predictions for the $\frac{J}{\psi }$ helicity. The predictions apply as well to electroproduction at small $Q^2$.