Photon Dissociation Model for Vector-Meson Photoproduction

We show how the diffraction-dissociation approach can be formulated and used to yield detailed results for photoproduction of photon-like states such as $\rho$, $\omega$, and $\varphi$. The model is shown to yield a coherent description of both the qualitative and quantitative aspects of the relevant experiments, including the size and behavior of the cross sections, the mass shifting of the $\rho$ peak, and the nuclear $A$ dependence. We are able to extract from experiment scattering cross sections for the vector mesons and their effective photon couplings which are in accord with other data, insofar as they are available. We suggest a number of interesting experiments that can be used to test the model and the $\varphi -\omega$ mixing theory for the $S{U}_3$ structure of the photon.