Measurement of polarization observables of the associated strangeness production in proton proton interactions

F. Hauenstein; E. Borodina; H. Clement; E. Doroshkevich; R. Dzhygadlo; K. Ehrhardt; W. Eyrich; W. Gast; A. Gillitzer; D. Grzonka; S. Jowzaee; P. Klaja; L. Kober; K. Kilian; M. Krapp; M. Mertens; P. Moskal; J. Ritman; E. Roderburg; M. Röder; W. Schroeder; T. Sefzick; J. Smyrski; P. Wintz; P. Wüstner

doi:10.1140/epja/i2016-16337-1

2022 Impact factor 2.7

Hadrons and Nuclei

Eur. Phys. J. A (2016) 52: 337
https://doi.org/10.1140/epja/i2016-16337-1

Regular Article - Experimental Physics

Measurement of polarization observables of the associated strangeness production in proton proton interactions

The COSY-TOF Collaboration
F. Hauenstein¹^,5, E. Borodina¹, H. Clement⁶^,7, E. Doroshkevich⁶^,7, R. Dzhygadlo¹, K. Ehrhardt⁶^,7, W. Eyrich⁵, W. Gast¹, A. Gillitzer¹, D. Grzonka¹, S. Jowzaee¹^,8, P. Klaja¹^,5, L. Kober⁵, K. Kilian¹, M. Krapp⁵, M. Mertens¹, P. Moskal⁸, J. Ritman¹^,2^,3^,9, E. Roderburg¹^*, M. Röder¹, W. Schroeder¹⁰, T. Sefzick¹, J. Smyrski⁸, P. Wintz¹ and P. Wüstner⁴

¹ Institut für Kernphysik, Forschungszentrum Jülich, 52428, Jülich, Germany
² Forschungszentrum Jülich, Jülich Aachen Research Alliance, Forces and Matter Experiments (JARA-FAME), 52428, Jülich, Germany
³ RWTH Aachen, 52056, Aachen, Germany
⁴ Zentralinstitut für Engineering, Elektronik und Analytik, 52428, Jülich, Germany
⁵ Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058, Erlangen, Germany
⁶ Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, 72076, Tübingen, Germany
⁷ Kepler Center for Astro and Particle Physics, University of Tübingen, Auf der Morgenstelle 14, 72076, Tübingen, Germany
⁸ Institute of Physics, Jagellonian University, PL-30-348, Cracow, Poland
⁹ Experimentalphysik I, Ruhr-Universität Bochum, 44780, Bochum, Germany
¹⁰ Corporate Development, Forschungszentrum Jülich, 52428, Jülich, Germany

^* e-mail: e.roderburg@fz-juelich.de

Received: 21 July 2016
Accepted: 28 October 2016
Published online: 21 November 2016

Abstract

The polarization, the analyzing power, and the spin transfer coefficient of the reaction pp pK ⁺ were measured at beam momenta of 2.70GeV/c and 2.95GeV/c corresponding to excess energies of 122MeV and 204MeV. While the analyzing power and the spin transfer coefficient do not change significantly with the excess energy, the polarization varies strongly and changes its sign. As this is the first measurement of polarization observables below an excess energy of 200MeV, the change of the sign of the polarization was not observed before. The high statistics of the data ( 200 k events for each momentum) enables detailed studies of the dependence of the polarization and the analyzing power on the center-of-mass momentum of the particles. The results of the spin transfer coefficient are in qualitative agreement with the DISTO experiment. The polarization data of 2.95GeV/c are only conform with the DISTO experiment, while both the 2.70GeV/c and 2.95GeV/c data differ strongly from all previous measurements, whether exclusive or inclusive.