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Exclusive production of the isoscalar vector mesons $\omega$ and $\phi$ ismeasured with a 190 GeV$/c$ proton beam impinging on a liquid hydrogen target.Cross section ratios are determined in three intervals of the Feynman variable$x_{F}$ of the fast proton. A significant violation of the OZI rule is found,confirming earlier findings. Its kinematic dependence on $x_{F}$ and on theinvariant mass $M_{p\mathrm{V}}$ of the system formed by fast proton$p_\mathrm{fast}$ and vector meson $V$ is discussed in terms of diffractiveproduction of $p_\mathrm{fast}V$ resonances in competition with centralproduction. The measurement of the spin density matrix element $\rho_{00}$ ofthe vector mesons in different selected reference frames provides anotherhandle to distinguish the contributions of these two major reaction types.Again, dependences of the alignment on $x_{F}$ and on $M_{p\mathrm{V}}$ arefound. Most of the observations can be traced back to the existence of severalexcited baryon states contributing to $\omega$ production which are absent inthe case of the $\phi$ meson. Removing the low-mass $M_{p\mathrm{V}}$ resonantregion, the OZI rule is found to be violated by a factor of eight,independently of $x_\mathrm{F}$.

Spin alignment and violation of the OZI rule in exclusive $\omega$ and $\phi$ production in pp collisions