Production of $\omega$ and $\phi$ Mesons in Near-Threshold $\pi N$ Reactions: Baryon Resonances and Validity of the OZI Rule

Abstract

Results of a combined analysis are presented for the production of $\omega$ and $\phi$ mesons in $\pi N$ reactions in the near-threshold region using throughoutly a conventional ''non-strange'' dynamics based on such processes which are allowed by the non-ideal $\omega-\phi$ mixing. We show that strong interferences of the $t$ (meson exchange) and $s$ and $u$ (nucleon and nucleon resonance) channels differ significantly in $\omega$ and $\phi$ production amplitudes. This leads to a decrease of the relative yields in comparison with expectations based on one-channel models with standard $\omega - \phi$ mixing. We find a strong and non-trivial difference between observables in $\omega$ and $\phi$ production reactions caused by the different role of the nucleon and nucleon resonance amplitudes. A series of predictions for the experimental study of this effect is presented.