Production of $\omega$ and $\phi$ mesons in near-threshold $\pi N$ reactions: Baryon resonances and the Okubo-Zweig-Iizuka rule

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 a conventional “nonstrange” dynamics based on processes that are allowed by the nonideal $\omega -\phi$ mixing. We show that the interferences of the t channel (meson exchange) and s, u channels (nucleon and nucleon-resonances) differ significantly for the $\omega$ and $\phi$ production amplitudes. This leads to a decrease of the relative yields, in comparison with the expectations based on a one-component amplitude with standard $\omega -\phi$ mixing. We find a strong and nontrivial difference between observables in $\omega$ and $\phi$ production reactions caused by the different roles of the nucleon and nucleon-resonance amplitudes. A series of predictions for the experimental study of this effect is presented.