Analysis of the e⁺e⁻ → η J/ψ cross section within a unitarized coupled-channel approach

We investigate the e⁺ e⁻ → η J/ψ e + e - → η J / ψ cross section by employing a model that combines relativistic Breit–Wigner amplitudes with a unitarized coupled-channel approach to account for resonant and non-resonant contributions, respectively. By performing a global fit to the BESIII experimental data, we determine the essential free parameters of the transition amplitudes. Furthermore, we analyze the role of a dynamically generated DD̄^* D D ¯ ∗ pole near 3.88 GeV and demonstrate its critical contribution to shaping the observed cross-section line shape.