Observation of resonance-like behavior of the pp → {pp}sπ0 reaction around √s = 2.65 GeV

The pp → {pp }s π 0 reaction, where {pp }s denotes a diproton, i.e. an unbound interacting proton pair in the 1 S 0 state, has been studied in order to obtain the forward differential cross section dσ /d Ω at 11 energy values in the region of 0.8–2.8 GeV. A resonance-like peak with the energy E 0 = 2.647 ± 0.005 GeV and the width Γ = 0.26 ± 0.03 GeV has been observed in the energy dependence of the differential cross section dσ /d Ω at zero angle. The slope of the angular dependence for the energies in the peak region is different compared with the energies around it. Possible implications on this phenomenon are discussed.