Photoproduction Constraints on J/ψ-Nucleon Interactions

Using J/ψ and open charm photoproduction data, we apply the vector meson dominance model to obtain constraints on the energy dependence of the inelastic J/ψ-nucleon cross section. Predictions of short distance QCD are in accord with these constraints, while recently proposed hadronic models for J/ψ dissociation strongly violate them. The energy dependence of the inelastic J/ψ-nucleon cross section σ ψN (s) is of great importance in understanding J/ψ suppression as signature for colour deconfinement in high energy nuclear collisions [1]. Calculations based on short distance QCD predict a strong threshold damping of σ ψN (s), due to the suppression of high momentum gluons by the gluon distribution function in nucleons [2]-[5]; this damping persists also when finite target mass corrections are taken into account [6]. In contrast to such QCD studies, several recently proposed models based on hadron exchange suggest large threshold values of σ ψN (s) [7] [9]. The aim of this note is to show that available J/ψ and open charm photoproduction data can do much to clarify the situation. The existing empirical information on J/ψ-hadron interactions comes from photoproduction and the vector meson dominance model (VMD) [10], which relates ee → ψ, γN → ψN and ψ−N data [11]. It is based on the assumption that fluctuations of the photon into quark-antiquark pairs are dominated by the corresponding hadronic resonances. As a result, the diffractive J/ψ-photoproduction cross section is related to elastic ψ−N scattering, σ(γN → ψN) = (