The COSY-11 collaboration measured the pp -> ppeta and pp -> ppeta reactions in order to perform comparative studies of the interactions within the proton-proton-meson system. This thesis presents in detail the analysis of the pp -> ppeta reaction which was measured at the proton beam momentum of 3.260 GeV/c. The elaboration results in differential distributions of squared invariant proton-proton (s_pp) and proton-eta (s_peta) masses, as well as in angular distributions and the total cross section at an excess energy of 16.4 MeV. The differential distributions s_pp and s_peta are compared to theoretical predictions and to the analogous spectra determined for the pp -> ppeta reaction. The comparison of the results for the eta and eta meson production rather excludes the hypothesis that the enhancement observed in the invariant mass distributions is due to the meson-proton interaction. Further, the shapes of the distributions do not favour any of the postulated theoretical models.
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