Abstract. The production of the Λ and Σ 0 hyperons has been measured via the pp → pK + Λ/Σ 0 reaction at the internal COSY-11 facility in the excess energy range between 14 and 60 MeV. The transition of the Λ/Σ 0 cross section ratio from about 28 at Q ≤ 13 M eV to the high energy level of about 2.5 is covered by the data showing a strong decrease of the ratio between 10 and 20 MeV excess energy. Effects from the final state interactions in the p − Σ 0 channel seems to be much smaller compared to the p − Λ one. Estimates of the effective range parameters are given for the N Λ and the N Σ systems.

The production of η mesons has been measured in the proton-proton interaction close to the reaction threshold using the COSY-11 internal facility at the cooler synchrotron COSY. Total cross sections were determined for eight different excess energies (ǫ) in the range from ǫ = 0.5 MeV to ǫ = 5.4 MeV.The energy dependence of the total cross section is well described by the available phase-space volume weighted by FSI factors for the proton-proton and proton-η pairs.