In many reactions leading to excitations of the nucleon, the Roper resonance \ (N^* (1440) \) can be sensed only very indirectly by complex partial-wave analyses. In nucleon–nucleon collisions the isoscalar single-pion production as well as specific two-pion production channels present the Roper excitation free of competing resonance processes at a mass of 1370 MeV and a width of 150 MeV. A detailed analysis points to the formation of \ (N^* (1440) N\) dibaryonic systems during the nucleon–nucleon collision process similar to what is known from the \ ( (1232) N\) threshold. Abstract Published by the Jagiellonian University 2026 authors
H. Clement (Tue,) studied this question.