Investigation of the Σ ^0 Production Mechanism in p(3.5 GeV)+p Collisions

The production of Σ ^0 hyperons in proton proton collisions at a beam kinetic energy of 3.5 GeV impinging on a liquid hydrogen target was investigated using data collected with the HADES setup. The total production cross section is found to be σ (pK^+Σ ^0) = 17.7 ± 1.7 (stat) ± 1.6 (syst) µb. Differential cross section distributions of the exclusive channel pp → pK^+Σ ^0 were analyzed in the center-of-mass, Gottfried–Jackson and helicity reference frames for the first time at the excess energy of 556 MeV. The data support the interplay between pion and kaon exchange mechanisms and clearly demonstrate the contribution of interfering nucleon resonances decaying to K^+Σ ^0 . The Bonn–Gatchina partial wave analysis was employed to analyse the data. Due to the limited statistics, it was not possible to obtain an unambiguous determination of the relative contribution of intermediate nucleon resonances to the final state. However nucleon resonances with masses around 1.710 GeV/c^2 ( N^*(1710) ) and 1.900 GeV/c^2 ( N^*(1900) or Δ ^*(1900) ) are preferred by the fit.