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 Juelich. The experimental technique applied at the internal COSY-11 facility -- designed for meson production studies at small excess energy -- is outlined. The threshold excitation functions for the kaon--hyperon production via the reactions pp → pK+Λ and pp → pK+Σ0 are presented. The magnitude of the production amplitudes is compared at equal excess energies, and physical implications of the observed Σ0 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 Λ--p channel. With the possibility of detecting all final state particles the elementary antikaon production in the reaction pp → ppK+k- has been investigated. Results on the exclusive total cross section fix the scale of the strangeness dissociation into two kaons