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HK: Fachverband Physik der Hadronen und Kerne
HK 35: Elektromagnetische und Hadronische Sonden
HK 35.3: Talk
Wednesday, March 14, 2007, 17:30–17:45, A
Study of the near threshold η meson production in the deuteron-proton collision. — •Cezary Piskor-Ignatowicz, Pawel Moskal, and Jerzy Smyrski for the COSY-11 collaboration — Institute of Physics, Jagellonian University, 30-059 Cracow, Poland
The interaction of the η meson in the three nucleon system is intensively studied on theoretical grounds. This topic is of the special interest due to the possible existence of η-nucleus bound or quasi-bound states. Thus, near threshold experimental data on the production of the η meson in deuteron-proton collisions are of great importance. An improvement of the existing data base is also crucial for the understanding of the η meson production mechanism and the interaction of this meson with the nucleon. Measurements of excitation functions for the dp→ 3 HeX and dp→ dpX, (X = π0,η) reactions [1] near the η production threshold have been conducted by the COSY-11 collaboration using a deuteron beam of the cooler synchrotron COSY and a hydrogen cluster target. For the 3 HeX channel the data were taken during a slow ramping of the COSY deuteron beam momentum and for the dpX channel at three discrete beam energies. The excitation function for the reaction dp→ 3 Heπ0 does not show any structure which could originate from the decay of a 3 He−η bound state. In the excitation curve for the dp→ 3 HeX process, however, contrary to the SATURNE results, we observe no cusp near the η threshold. The excitation functions for the dp→ 3 Heπ0, dp→ 3 Heη, and dp→ d p η reactions near threshold for the η meson production will be presented and discussed. [1] J. Smyrski et al., Acta Phys. Slovaca 56 213 (2006).