η′Production in proton-proton scattering close to threshold

The pp → pp η′(958) reaction has been measured at the cooler synchrotron COSY at Jülich using the internal beam and the COSY-11 facility. The total cross sections at the four different excess energies Q=1.5, 1.7, 29, and 4.1MeV have been evaluated to be σ=2.5±0.5, 2.9±1.1, 12.7±3.2, and 25.2±3.6 nb, respectively. In this region of excess energy the η′(958) cross sections are much lower compared to those of the μ0 and η production. © 1998 The American Physical Society.