J/ψ suppression in hadron-nucleus collisions

We examine the production of J/ψ mesons in high energy hadron-nucleus collisions using models that account for both the initial state modification of parton distributions in nuclei and the final state interaction of the produced cc¯ pairs. We show that, at the energies of current fixed target experiments, J/ψ production through quark-antiquark annihilation gives the largest contribution at ${\mathit{x}}_{\mathit{F}}$>0.5 while gluon-gluon fusion dominates the production at smaller ${\mathit{x}}_{\mathit{F}}$. The observed J/ψ suppression at large ${\mathit{x}}_{\mathit{F}}$ is directly connected to nuclear shadowing in deeply inelastic scattering. We find that a 6–8 mb cc¯-nucleon cross section is needed to explain the data on J/ψ suppression if a simple incoherent multiple scattering formalism is used for the final state interactions. We then provide a more complete model to incorporate the effects of final state multiple soft scatterings. With only one parameter, this model can fit both the normalization and A dependence of the data for a variety of nuclei.