Abstract :
We give reasons for the existence of the NN decoupled dibaryon resonance d1★ (1956). Strong evidence for its presence has first been found in the energy spectrum of coincident photons emitted at ±90° from the pp → γγX process at 216 MeV measured by the DIB2γ collaboration at JINR. As further experimental indications of the d1★(1956) existence we present those found in the available photon energy spectra of npγ, pdγ, and pAγ reactions below the pion threshold. It is noted that serious discrepancies between the npγ and pdγ experimental cross sections and theoretical calculations can reasonably be explained by the fact that the latter did not take into account the d1★ effect.
