The Roper resonance \ (N^ (1440) \) was discovered by David Roper in 1964 through sophisticated partial-wave analyses of \ (N\) scattering data. However, the first direct observation of the Roper resonance peak in the \ (N\) invariant mass spectrum was only realized 40 years later from the charmonium decay \ (J/ pn ^+ + c. c. \) at the Beijing Electron–Positron Collider. Further observations of the Roper resonance production from various charmonium decays helped reveal its multiquark nature, with a large \ (N\) component. Abstract Published by the Jagiellonian University 2026 authors
B-S ZOU (Tue,) studied this question.