Observation of the spin alignment of the ϱ0-meson produced in ¯pp interactions at 22.4 and 5.7 GeV/cстатья
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Аннотация:Studying the 0-meson production in pp interactions at 22.4 GeV/c and in 4-prong annhilation channels of pp interactions at 5.7 GeV/c, we have observed an essential 0-meson spin alignment. The values of the 00 element of the 0-meson spin density matrix (thez-axis is directed along the normal to the production plane) are equal to 0.08 0.07 and 0.55 0.03, respectively, i.e. the 0-meson spin lies preferably in the production plane. The absence of such an effect in pp interactions at 12 and 24 GeV/c and also the essentially larger 0 production cross section in pp interactions at these energies make it possible to connect the observed 0-meson spin alignment with the annihilation processes. The character of the observed spin alignment is unexpected from the point of view of usual models, e.g. multiperipheral models. This effect could be described by the spontaneous polarization of quarks and antiquarks during the state preceding their recombination into mesons.