The COSY-11 collaboration has measured the total cross section for the pp->pp eta' and pp->pp eta reactions in the excess energy range from Q=1.5MeV to Q=23.6MeV and from Q=0.5MeV to Q=5.4MeV, respectively. The obtained results agree well with the measurements performed at the accelerators SATURNE and CELSIUS. The energy dependence of the total cross section determined for the pp->pp eta' reaction is well described by calculations based on the phase space volume and the proton-proton FSI implying a rather small proton-eta' interaction. In contrary, close to threshold the total cross section of the pp->pp eta reaction differs significantly from the expectations based on the above assumtions, due to the strong proton-eta interaction. These observations imply that proton-eta and proton-eta' interactions are of significantly different strength, albeit both these mesons have the same quantum numbers and very similar quark contents.
Thus we intend to study quantitatively the completely unknown proton-eta' interaction and also the not well established proton-eta interaction by the measurement of the differential cross sections.
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