Mechanism of NNΔ and NΔΔ resonances and Pd-3Heπ0 reaction

The pd-3Heπ reaction amplitudes at deuteron incident energies T = 500-1200 MeV are calculated in the three-body formulation where the NNN, NNΔ, and πN channels couple through the dibaryonic NN-NΔ-πd coupled interaction. The approximation is used that the NNΔ channel dominates in the intermediate states. The input dibaryonic interaction is made consistently with the pp-pp, pp-πd and πd-πd partial wave analysis results as well as the theoretical result of the πNN dynamics. A remarkable finding is that the JP = 5/2+ reaction amplitude loops anticlockwise in the Argand plot with the magnitude maximum at T = 850 MeV, 100 MeV below the NNΔ threshold. This paper suggests the existence of a guasi bound state of the NNΔ system with the binding energy of a few 10 MeV