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Spin alignment and violation of the OZI rule in exclusive $\omega$ and $\phi$ production in $pp$ collisionsстатья
- Авторы: Adolph C., COMPASS Collaboration, Sapozhnikov M.
- Журнал: Nuclear Physics
- Год издания: 2014
- DOI: 10.1016/j.nuclphysb.2014.07.020
- Аннотация: Exclusive production of the isoscalar vector mesons ω and ϕ is measured with a 190 GeV/c190 GeV/c proton beam impinging on a liquid hydrogen target. Cross section ratios are determined in three intervals of the Feynman variable xFxF of the fast proton. A significant violation of the OZI rule is found, confirming earlier findings. Its kinematic dependence on xFxF and on the invariant mass MpVMpV of the system formed by fast proton pfastpfast and vector meson V is discussed in terms of diffractive production of pfastVpfastV resonances in competition with central production. The measurement of the spin density matrix element ρ00ρ00 of the vector mesons in different selected reference frames provides another handle to distinguish the contributions of these two major reaction types. Again, dependences of the alignment on xFxF and on MpVMpV are found. Most of the observations can be traced back to the existence of several excited baryon states contributing to ω production which are absent in the case of the ϕ meson. Removing the low-mass MpVMpV resonant region, the OZI rule is found to be violated by a factor of eight, independently of xFxF.
- Добавил в систему: Сапожников Михаил Григорьевич