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EPJ A - Hadrons and Nuclei
Hadrons and Nuclei


Eur. Phys. J. A 12, 117-120 (2001)

Measurements of the spin rotation parameter A in the elastic pion-proton scattering in the D13(1700) resonance region

I.G. Alekseev1, N.A. Bazhanov2, Yu.A. Beloglazov3, P.E. Budkovsky1, E.I. Bunyatova2, V.P. Kanavets1, A.I. Kovalev3, L.I. Koroleva1, S.P. Kruglov3, B.V. Morozov1, V.M. Nesterov1, D.V. Novinsky3, V.V. Ryltsov1, V.A. Shchedrov3, A.D. Sulimov1, V.V. Sumachev3, D.N. Svirida1, V.Yu. Trautman3 and V.V. Zhurkin1

1  Institute for Theoretical and Experimental Physics, Moscow, 117259, Russia
2  Joint Institute for Nuclear research, Dubna, Moscow district, 141980, Russia
3  Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, 188300, Russia

Vadim.Kanavets@itep.ru
sumachev@pcfarm.pnpi.spb.ru

(Received: 17 August 2001 / Revised version: 10 September 2001 Communicated by V.V. Anisovich)

Abstract
The spin rotation parameters A and R were measured for the elastic pion-proton scattering by the PNPI-ITEP collaboration in the D13(1700) resonance region. The main goal of the experimental program is to resolve the current partial-wave analyses (PWA) uncertainties. Simultaneously with A and R the polarization parameter P was measured with the purpose to improve the experimental database and estimate systematic errors. The constraint which demands a smooth energy dependence of all $\pi^-p$ transverse amplitude zeros in the complex plane together with the new experimental data on A parameter can lead to the conclusion that the Barrelet branch of "zero trajectories" is chosen improperly in PWA of the Carnegie-Mellon-Lawrence-Berkely-Laboratory groups at the range of the pion beam momentum near 1.0 GeV/c. The setup included a longitudinally polarized proton target with superconductive magnet, multiwire spark chambers and carbon polarimeter with thick filter. The experiment was performed at the ITEP proton synchrotron, Moscow.

PACS
13.75.Gx - Pion-baryon interactions.
13.85.Dz - Elastic scattering.
13.88.+e - Polarization in interactions and scattering.
14.20.Gk - Baryon resonances with S=0 .

© Società Italiana di Fisica, Springer-Verlag 2001

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