Energy dependence of the near-threshold total cross-section for the pp→ ppη′ reaction

Abstract

Total cross sections for the pp→ ppη′ reaction have been measured in the excess energy range from Q=1.53 MeV to Q=23.64 MeV. The experiment has been performed at the internal installation COSY-11 [1] using a stochastically cooled proton beam of the COoler SYnchrotron COSY [2] and a hydrogen cluster target [3, 4]. The determined energy dependence of the total cross section weakens the hypothesis of the S-wave repulsive interaction between the η′ meson and the proton [5, 6]. New data agree well with predictions based on the phase-space distribution modified by the proton-proton final-state-interaction (FSI) only.