J/\Psi N and Psi' N total cross sections from photoproduction data: failure of vector dominance

Abstract

Values for the cross sections ${\sigma }_{tot}^{\Psi N}$ and ${\sigma }_{tot}^{{\Psi }^{\prime }N}$ are of crucial importance, once one wants to understand nuclear suppression of $J/\Psi$(${\Psi }^{\prime }$) in a search for the quark gluon plasma. Quoted values are usually extracted from $\gamma N\to J/\Psi ({\Psi }^{\prime })N$ data via the vector dominance model (VDM) and are very small compared with expectations from QCD. The validity of QCD is questioned. When the VDM is extended to a multi-channel case, the $\gamma N$ data lead to a value $2.8\pm 0.12mb<{\sigma }_{tot}^{\Psi N}(\sqrt{s}=10GeV)<4.1\pm 0.15mb$, which is a factor 3 larger than the VDM prediction. Errors are due to experimental input, and the corridor shows the theoretical uncertainty. We also derive from the data ${\sigma }_{tot}^{{\Psi }^{\prime }N}/{\sigma }_{tot}^{J/\Psi N}\approx 4$, where we could not estimate the theoretical uncertainty.

Comments: 13 pages, 2 Postscript figures