Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 30: Elektromagnetische und hadronische Proben V

HK 30.1: Group Report

Wednesday, March 19, 2003, 14:00–14:30, B

Study of the hadronic interaction of the η meson with nucleons — •P. Moskal — Institut für Kernphysik, Forschungszentrum Jülich, Germany — Institute of Physics, Jagellonian University, ul. Reymonta 4, 30-059 Cracow, Poland

The production of the η meson in elementary proton-proton collisions has been investigated at the synchrotrons CELSIUS, COSY and SATURNE.

The experimental data allows to establish that the dependence of the total cross section on the excess energy is predominantly determined by the final state interaction among the produced particles. In case of the pp → ppη reaction the achieved precision permits to distinguish the effect of the η-nucleon interaction from the overwhelming influence of the nucleon-nucleon distortion.

A modification of the phase space occupation due to the η pp interaction is evidently seen in the high statistics exclusive measurements of the pp→ ppη reaction recently performed at the COSY-11 facility at COSY.

he world available data will be interpreted in view of the production mechanism of the η meson in the hadronic interaction and the η-nucleon interaction. The elaborated [1,2] and new results  [3,4] of the COSY-11 collaboration obtained with the both polarised and unpolarized proton beams will be discussed.

[1] COSY-11: J. Smyrski et al., Phys. Lett. B 474 (2000) 182.

[2] COSY-11: P. Moskal et al.,Phys. Lett. B 474 (2000) 416.

[3] COSY-11: P. Winter et al.,Phys. Lett. B 544 (2002) 251.

[4] COSY-11: P. Moskal et al.,πN Newsletter 16 (2002) 367.