Bonn 2010 – wissenschaftliches Programm
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.