Abstract
The π− p interactions with at least one charged secondary produced at polar angle ∼90° in c.m.s. and having the transverse momentum above 1 GeV/c were investigated. The data were obtained using streamer chamber magnetic spectrometer RISK at 38 GeV/c π beam from Serpukhov accelerator. The analyzis of associated production in reconstructed events suggests, that if the transverse momentum of a pair of oppositely charged secondaries compensates the trigger particlep ⊥ practically completely, this pair is the product of the ρ0 decay in marked fraction of such events. We observed a large spin-alignment for the ρ0-mesons selected as described above: the probability of zero spin projection onto the normal to the ρ0 production plane is equal to ρ T00 =0.86±0.23. The enhancement of the number of events, in which the ρ0 picks up practically full momentum transfer carrying by the exchange, and also the enlarged tensor polarization for the ρ0-mesons in these events could be qualitatively explained as manifestation of direct ρ0-production via the QCD higher twist processes in the highp ⊥π− p collisions. At the same time, the observed effects are markedly larger than the values predicted with QCD model in which the higher twist corrections were included.
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RISK Collaboration., Bannikov, A.V., Bohm, J. et al. Evidence for higher twist mechanisms in highp ⊥π− p events with prompt ρ0 production at 38 GeV/c. Z. Phys. C - Particles and Fields 49, 245–249 (1991). https://doi.org/10.1007/BF01555497
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DOI: https://doi.org/10.1007/BF01555497