Revisiting the c^+ K⁰ p reaction: the role of N^* (1535), N^* (1650) and (1620)

Abstract We perform a theoretical study of the weak decay c^+ K⁰ p Λ c + → K ¯ 0 η p using a coupled-channel chiral unitary approach that incorporates both pseudoscalar-baryon and vector-baryon interactions. Our framework includes contributions from both internal and external weak emission mechanisms, as well as strong final state interactions. We assume that the N^* (1535) N ∗ (1535) and N^* (1650) N ∗ (1650) resonances are dynamically generated through meson-baryon scattering and they appear as distinct structures in the p η p invariant mass distributions. A clear peak also appears in the K⁰ p K ¯ 0 p invariant mass distribution around 1620 MeV, associated with the dynamically generated (1620) Σ (1620) resonance. Notably, this work provides the first theoretical description of the simultaneous observation of these two related N^* N ∗ resonances in the same meson-baryon final state. Our results highlight the crucial role of final state interaction and the interplay between different weak decay topologies in shaping the resonance patterns. These findings offer new insights into the nature of nucleon excitations and support the interpretation of N^* (1535) N ∗ (1535) and N^* (1650) N ∗ (1650) as dynamically generated states. Moreover, the identification of the (1620) Σ (1620) further supports the picture of hadronic molecular structures emerging from meson-baryon interactions in the non-perturbative QCD regime.