J/ψ-meson photoproduction off the nucleon in a dynamical model

• Published in: Physics letters. B Vol. 868; p. 139725
• Main Author: Kim, Sang-Ho
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2025; Elsevier
• Subjects: Final state interactions; J/ψ photoproduction; Meson exchanges; Pomeron exchange; Pomeron exchange; Meson exchanges; J/ψ photoproduction; Final state interactions
• ISSN: 0370-2693
• DOI: 10.1016/j.physletb.2025.139725

The photoproduction of J/ψ meson off the nucleon is investigated using a dynamical model based on a Hamiltonian that describes the reaction mechanisms involving meson-exchange and direct J/ψ-radiation terms. Pomeron exchange is also included to account for the monotonically increasing high-energy behavior of the cross section. To explore the low-energy mechanism, we scrutinize the role of light-meson [π0(135), η(548), η′(958), f1(1285)] and charmonium-meson [ηc(1S), χc0(1P), χc1(1P), ηc(2S), χc1(3872)] exchanges in the t-channel diagram. Most of the coupling constants are determined from the radiative decays of the J/ψ or the relevant charmonium mesons. The final J/ψ-N interaction is described by gluon-exchange and direct J/ψN coupling. The parameters of the Hamiltonian are fitted using the latest GlueX and J/ψ-007 experiments at the Jefferson Laboratory (JLab). We find that among the meson-exchange terms, the light mesons η(548) and η′(958) make the most significant contributions to γp→J/ψp, while the effect of charmonium mesons is relatively minor. The final-state interaction (FSI) contribution is found to be 1 - 2 orders of magnitude smaller than that of the Born term, but becomes significant near the threshold when a Yukawa-type potential is employed for the charmonium-nucleon interaction. The resulting total and t-dependent differential cross sections show good agreement with the JLab data. High-precision angular measurements near the threshold energy (Eγ⩽8.9 GeV) are highly desirable to clarify the role of the FSI term.