Systematics of J/ψ production in nuclear collisons

We present a comprehensive QCD-based model for the xf and nuclear dependences of heavy quarkonium production in photon-, hadron-, and nuclear-induced collisions. The calculated xf dependence reflects both leading-twist QCD fusion subprocesses and higher-twist intrinsic heavy-quark components of the hadron wavefunction. A-dependent effects due to final-state absorption, interactions with comovers, shadowing of parton distributions, and intrinsic heavy-quark components are identified. The model is compared with data for J/ψ, ψ', and Υ production in pion-, proton-, and nucleus-nucleus collisions. (orig.)