Bonn 2010 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 5: Hadronenstruktur und -spektroskopie II

HK 5.4: Vortrag

Montag, 15. März 2010, 17:15–17:30, HG IV

Study of the ppK+nΣ+ reaction near threshold — •Yury Valdau — Forschungszentrum Jülich, Leo-Brandt-Straße, 52428 Jülich, Germany — Petersburg Nuclear Physics Institute of RAS, High Energy Physics Division, Meson Physics of a Condensed Matter Laboratory, 188300 Gatchina, Leningrad district, Russia

Three different hyperon channels, Λ, Σ0 and Σ+, contribute to K+ production in pp interactions close-to-threshold. While a lot of data exist for the Λ and Σ0 total production cross sections, there are only a few measurements of the third hyperon channel ppK+ n Σ+.

At ANKE-COSY the energy dependence of the Σ+ production total cross section was studied at four different proton beam energies between reaction threshold and 2.1 GeV. Our analysis of the Σ+ channel is based on a simultaneous measurement of three experimental observable: K+ inclusive spectra, K+ p missing mass spectra and individual particle momentum spectra from K+ π+ correlation events. Below the ppK+ n Λ π+ reaction threshold (∼ 2.02 GeV) the only source of K+ π+ correlations is Σ+ production. Thus, identification of K+ π+ coincidences allows us to identify the Σ+ reaction channel unambiguously below ∼2.0 GeV, and to estimate the total cross section. The extracted Σ+ production total cross sections should allow to describe K+ inclusive and K+ p correlation spectra using known Λ and Σ0 total cross sections as well.

The status of analysis and experimental results will be presented.

Supported by the COSY–FFE program.

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