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 pp→K⁺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 pp → K⁺ 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 pp → K⁺ 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.