High Energy Photo-Reactions and Generalized Vector Meson Dominance Model in the Relativistically Extended Quark Model

A generalized vector meson dominance model which is derived from the quark model with the relativistically extended internal structure is applied to high energy photo-reactions, i.e., e+e- → vector meson (Vλ0), Compton scattering and photoproductions of vector mesons. In this model it is predicted that infinite numbers of vector mesons must be introduced to describe the currents of hadrons. It is shown that the discrepancy among photo-vector meson transition couplings derived from the reactions e+e- →Vλ0, γp→γp, γd→γd and γp→Vλ0p with the aid of the usual vector meson dominance model in which only ρ-, ω- and φ-mesons are adopted is corrected and the couplings of all the reactions can consistently be reproduced by introducing the infinite numbers of vector mesons predicted by our model. It is also shown that the contributions of mesons other than ρ, ω and φ are expected to become remarkable at large momentum transfers. Predictions of Γ(Vλ0→e+e-) and dσ/dt(γp→Vλ0p)|t=0 are presented. Comparison of our results with some experiments on the first-excited vector meson is also carried out.