The study of the proton-proton collisions at the beam momentum 1581 MeV/c

The new data on the elastic pp and single-pion production reaction pp → pnπ ⁺ taken at the incident proton momentum 1581 MeV/c are presented. To extract contributions of the leading partial waves the single-pion production data are analyzed in the framework of the event-by-event maximum-likelihood method together with pp → ppπ ⁺ data measured earlier and the pp → pnπ ⁺ data taken at 1628 MeV/c. The analysis shows that at 1581 MeV/c the largest contributions stem from the ³ P ₂, ³ P ₁, ³ P ₀ and ³ F ₂ initial partial waves. From these partial waves we also deduce contributions for the production of the Δ(1232) and N(1440) states.