Abstract:

The main advantage of the channels with the ¹S₀ diproton (pp_s) formation over the deuteron channels is the relative simplicity of the diproton wave function which greatly simplifies the partial wave analysis. The difference in isospins of the final state of a nucleon-nucleon pair in the diproton and deuteron channels provides additional opportunities for the analysis of nucleon-nucleon interactions.

The seminar will present the results of studying the pp → pp_s π⁰ and pp → pp_s γ reactions at the energies of 0.35−0.8 GeV, obtained within the ANKE-COSY program on the study of inelastic proton-proton collisions at intermediate energies with the final-state ¹S₀ diproton formation.

The reaction of hard bremsstrahlung with the ¹S₀ diproton formation pp → pp_s γ at the energies above the meson formation threshold was first observed at ANKE-COSY. The measurements have shown the dominant contribution of the Δ(1232) resonance to its cross section.

The energy and angular dependencies of the differential cross section dσ/dΩ and the analyzing power A_y were measured for the pp → pp_s π⁰ reaction. The results obtained for an energy of 353 MeV made it possible to carry out a joint partial-wave analysis of the processes pp → pp_s π⁰ and pn → pp_s π^–, required to determine the low-energy parameter d of the contact (NN)2π interaction in the chiral effective field theory. The dσ/dΩ and A_y values measured in the region of the ∆(1232) resonance excitation made it possible to refine the parameters of the ³P₂d dibaryon resonance state, to detect the resonance in the ³P₀s transition, and to measure the values of its mass and width. These results made an important contribution to the currently actively developing research on dibaryon resonances.

Based on the materials of the Ph.D. thesis.