J/(psi) suppression in electro-and hadroproduction : a conventional physics explanation

Abstract

Having in mind the importance of the phenomenon for the search for the quark-gluon plasma in the collision of heavy nuclei, we study the suppression of J/Ψ production in leptoproduction and hadroproduction on heavy nuclear targets. We here show that this phenomenon can be understood in terms of conventional physics, i.e., (i) perturbative QCD, (ii) the parton recombination implementation of shadowing in the initial state, (iii) the EMC efFect, and (iv) final state interactions of the produced J/Ψ with the hadronic debris of the nuclear target. Unlike previous calculations we include both the direct J/Ψ production and its production via radiative g decays (xj → J/Ψ + γ). We are able to reproduce the experimental data including their small-x behavior. We emphasize the importance of studying the xz dependence of the ratio σ(bA)/σ(bN), where b designates the beam and x2 is the momentum fraction of the parton from the nuclear target.