Two-proton correlation function for the pp → pp + η and pp → pp + pions reactions

For the very first time, the correlation femtoscopy method is applied to a kinematically complete measurement of meson production in the collisions of hadrons. A two-proton correlation function was derived from the data for the pp → ppX reaction, measured near the threshold of η meson production. A technique developed for the purpose of this analysis permitted the correlation function to be established separately for the production of the pp + η and of the pp + pions systems. The shape of the two-proton correlation function for ppη differs from that for pp(pions) and both do not show a peak structure, opposite to the results determined for inclusive measurements of heavy ion collisions.