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 . In addition, within a Dalitz plot analysis the spin-averaged S-wave scattering parameters could be extracted for the Lambda-p channel .
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.
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