Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 80: Hadron Structure and Spectroscopy I

HK 80.2: Talk

Friday, March 20, 2009, 11:15–11:30, H-ZO 20

Study of the pp→K⁺nΣ⁺ reaction near threshold — •Yury Valdau — Forschungszentrum Jülich, Leo-Brandt-Straße, 52428 Jülich

Three different hyperon channels Λ, Σ⁰ and Σ⁺ are contribute to the K⁺ production in pp interactions close-to-threshold. While there are a lot of data exist on the Λ and Σ⁰ total production cross sections, there are only few measurements of the third hyperon reaction 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 2.15 GeV. Our analysis of the Σ⁺ reaction 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 the K⁺ π⁺ correlation events. Below the pp → K⁺ n Λ π⁺ reaction threshold (∼2.02 GeV) the only source of the K⁺ π⁺ correlations can be Σ⁺ production. Thus, identification of K⁺ π⁺ allows us to identify Σ⁺ reaction channel unambiguously below ∼2.0 GeV, and estimate total cross section. 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.

The status of the analysis as well as preliminary experimental results will be presented.

Supported by the COSY–FFE program.