Gluon contribution to hadronicJψproduction

Abstract

Using the recent CERN and Fermilab measurements for $J/\psi$ production by ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\overline{p}$ beams we show, within the framework of quantum chromodynamics, that only a combined version of light-quark $q\overline{q}\to c\overline{c}$ fusion and gluon $\mathrm{gg}\to c\overline{c}$ fusion mechanisms can account for the various total-cross-section beam ratios as well as for the observed $x_F$ distributions.