Evidence for higher twist mechanisms in highp ⊥π− p events with prompt ρ0 production at 38 GeV/c

Autor: Z. Krumstein, A.K. Javrishvili, A.V. Bannikov, L. S. Vertogradov, A.I. Kharchilava, T. Gemesy, J. Krasznovszky, G.A. Shelkov, Yu.P. Merekov, K. Šafařik, Stefan Valkar, V.I. Petrukhin, S. Nedev, K. Piska, A. I. Shklovskaja, L. Jenik, Ya.V. Grishkevich, J. Bohm, V. Krysteva, G. Pinter, T. A. Lomtadze, W. Dominik, P. Zavada, V. N. Penev
Rok vydání: 1991
Předmět:
Zdroj: Zeitschrift für Physik C Particles and Fields. 49:245-249
ISSN: 1434-6052
0170-9739
Popis: 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 ρ00T=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.
Databáze: OpenAIRE
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