Hyperon and Charged Kaon Pair Production close to Threshold


Close to threshold data on the elementary kaon and antikaon production channels in the proton-proton interaction have been taken using the COSY-11 installation at the cooler synchrotron COSY Jülich.
The experimental technique applied at the internal COSY-11 facility - designed for meson production studies at small excess energies - is outlined. The threshold excitation functions for the kaon-hyperon production via the reactions pp->pK+Lambda and pp->pK+Sigma0 are presented. The magnitude of the production amplitudes is compared at equal excess energies and physical implications of the observed Sigma0 suppression in the threshold region are discussed [1]. In addition, within a Dalitz plot analysis the spin-averaged S-wave scattering parameters could be extracted for the Lambda-p channel [2].
With the possibility of detecting all final state particles the elementary antikaon production in the reaction pp->ppK+K- has been investigated [3,4]. Results on the exclusive total cross section fix the scale of the strangeness dissociation into two kaons and are compared to existing parametrizations and model calculations.

S.Sewerin, G Schepers et al., submitted for publication in Phys.Rev.Lett.
J.T.Balewski et al., Eur.Phys.J. A 2 (1998) 99
T.Lister, PhD thesis, Westfälische Wilhelms-Universität Münster (1998)
M.Wolke, PhD thesis, Rheinische Friedrich-Wilhelms-Universität Bonn (1997) and Report Jül-3532, Forschungszentrum Jülich.

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