Search for dibaryon resonances of masses between 2.16 and 2.32 GeV/c2 in the reaction γd → ppπ−

On the history of dibaryons and their final observation

“…Another intriguing structure in inclusive photo-induced pion production on the deuteron was reported from Saclay measurements, where a bumpy structure was observed in the energy dependence of the cross section around E γ = 400 MeV, which was associated with a dibaryon of mass 2230 MeV [133]. Subsequent exclusive high-resolution measurements of the γd → ppπ − reaction carried out at Bonn demonstrated that the ppπ − invariant mass distribution is flat showing no evidence for any dibaryon in the mass range 2160 -2320 MeV [134] -in agreement with corresponding pion-induced measurements carried out at Saclay [135] and SIN [136]. However, the Bonn data surprisingly revealed a small narrow Figure 1: Distribution of the pp-invariant mass M pp as observed in np-initiated single-pion production by the JINR bubble-chamber at Dubna [115] (top) and the magnetic spectrometer setup at ITEP [116] (bottom), respectively.…”

The Reaction D(e,pp)e 1π- on Polarized Deuteron at High Proton Momenta

“…The relative contribution of more complex reaction mechanisms grows in this kinematic area and these reactions require new models to describe the nucleon systems and hadron interactions. It is for these reasons the previous experiments in Hamburg [1] , Saclay [2] and Bonn [3,4] chose the search for dibarion states and observation of the (∆∆)-states as their main subject.…”