J/ψ production at the Tevatron and HERA: the effect of kT smearing

We study the effects of intrinsic transverse momentum smearing on J/ψ production both at the Tevatron and at HERA. For the case of large-pT J/ψ production at the Tevatron, the effects due to kT smearing are mild. On the other hand, inelastic J/ψ photoproduction at HERA is very sensitive to the kT smearing and, in fact, with a reasonable value of 〈kT〉 it is possible to resolve the large-z discrepancy seen by comparing non-relativistic QCD (NRQCD) predictions with the HERA data. We conclude that, with the present kinematic cuts, photoproduction at HERA is not a good test of NRQCD.