Nucleonic resonance excitations and "missing resonances" in the $\omega$ meson photoproduction

Abstract

In this work, an improved quark model approach to the $\omega$ meson photoproduction with an effective Lagrangian is reported. The {\it t}-channel {\it natural} parity exchange is consistently taken into account through the Pomeron exchange, while the {\it unnatural} parity exchange is described by the ${\pi }^0$ exchange. It shows that with very limited number of parameters, all the available experimental data in the low energy regime can be consistently accounted for in this framework. Effects from the intermediate nucleonic resonances are investigated in several polarization observables. The sensitivities of these observables to the resonance effects are probably the best way for identifying those so-called "missing resonances" in the baryon spectrum.

Comments: Contribution to "8th International Conference on Hadron Spectroscopy (Hadron'99)", IHEP-Beijing, P.R. China, August 24-28, 1999, to appear in Nucl. Phys. A