Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 57: Hadron Structure and Spectroscopy II

HK 57.8: Talk

Wednesday, March 18, 2009, 18:15–18:30, H-ZO 30

Search for the He−η bound states with WASA-at-COSY — •Wojciech Krzemien — Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany — Jagiellonian University, Cracow, Poland

We conduct a high sensitivity search for the He−η bound state with WASA-at-COSY facility, via measurement of the excitation functions for the dd → ³He p π⁻, pd→ p p p π⁻, pd→ p d π⁰ , reactions where the outgoing nucleon-pion pairs originate from the absorption of the η meson on a nucleon inside the He nucleus. Precise determination of the profile of the expected Breit-Wigner distribution in the excitation curves will allow to determine the binding energy and the width of the He−η bound state. In June 2008, first measurement of the excitation functions for the dd → ³Hepπ⁻ reaction was performed. In the experiment we used slowly ramped COSY deutron beam scanning the range of momenta corresponding to the variation of the excess energy for the Heη system from - 60 MeV up to 20 MeV. Preliminary results from the ongoing analysis will be presented. Supported by BMBF and Wallenberg Foundation.