Near-threshold η meson production in proton-proton collisions

Abstract 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 ( ϵ ) in the range from ϵ =0.5 MeV to ϵ =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.