Hadronic models for the photoproduction ofψ's

Abstract

We examine the photoproduction of the $\psi \mathrm{}\left(3095\right)\mathrm{}$ within the context of the assumption that the $\psi$ contains a pair of new fundamental constituents. Using an inequality based on unitarity, we derive a lower limit on the cross section $\sigma (\gamma p\to D\overline{D}+\mathrm{anything})\gtrsim 300$ nb where the $D\text{'}\mathrm{s}$ are hadrons carrying the new constituent bound to ordinary quarks. This suggests that it should be possible to detect $D\text{'}\mathrm{s}$ from their leptonic decays in $\gamma$ beams. Comparing the unitarity relations for $\gamma p\to \psi p$ and $\psi p\to \psi p$, we predict corrections to the vector-dominance hypothesis so that ${\sigma }_{\mathrm{tot}}\left(\psi p\right)$ is about a factor of two larger than expected. We discuss briefly the precision necessary for experiments on nuclear targets to test this prediction.