Köln 2004 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 11: Poster Session: Electromagnetic and Hadronic Probes
HK 11.18: Poster
Tuesday, March 9, 2004, 13:30–15:30, Foyer
Investigation of the Scalar Resonance a0+(980) at ANKE* — •V. Kleber — Institut für Kernphysik, Universität zu Köln, 50937 Köln / Forschungszentrum Jülich, 52425 Jülich
The scalar resonances a0/f0(980) have been observed in many experiments. However, their nature is not yet understood and they are interpreted, e.g., as genuine mesons (and thus members of the scalar nonet), KK molecules or compact qq–qq states. At COSY–Jülich an experimental program has been started, using the ANKE spectrometer, which aims at exclusive data on a0/f0 production from pp, pn, pd and dd interactions close to the KK threshold. The final goal will be the extraction of the charge-symmetry breaking a0/f0 mixing amplitude to shed light on the nature of the light scalar resonances. Here, we report about the first exclusive study of the reactions pp → dK+K^0 and pp → dπ+η. The measurements were performed at beam energies of Tp=2.65 and 2.83 GeV, corresponding to excess energies of 46 and 103 MeV above the KK threshold. From the measurement at the lower energy the total cross section of the reaction pp → dK+K^0 as well as differential distributions have been extracted. The main contribution to this reaction is interpreted as a0→K+K0 decays. The large background contribution from multiple-pion production to the reaction pp → dπ+η makes the analysis more complex than in the case of kaon production. The data at the higher energies are still under analysis, and the current status will be presented. * supported by FZJ, BMBF and DPG