Roper Resonance \(N^\ast (1440)\) from Charmonium Decays

The Roper resonance \(N^\ast (1440)\) was discovered by David Roper in 1964 through sophisticated partial-wave analyses of \(\pi N\) scattering data. However, the first direct observation of the Roper resonance peak in the \(\pi N\) invariant mass spectrum was only realized 40 years later from the charmonium decay \(J/\psi \to \bar pn\pi ^+ +\mathrm {c.c.}\) 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 \(\sigma N\) component. Abstract Published by the Jagiellonian University 2026 authors