We investigate S-wave coupled-channel effects in e+e− annihilation in the energy region s∈[4.0,5.5]GeV, including the open-charm final states Λc+Λˉc−, Ξc+Ξˉc−, Ξc0Ξˉc0, and ψ(2S)π+π−. Motivated by the recent high-precision BESIII measurements of the e+e−→Λc+Λˉc− cross section, which shows a nearly flat lineshape around 4.66GeV and a non-zero value right at threshold, in striking contrast to earlier Belle observation, we construct an effective coupled-channel framework by using short-ranged contact potentials in the heavy-quark limit.Two charmonium states, i.e. the ψ(4360) and ψ(4660), assigned as the 4S and 5S excitations, respectively, are explicitly included. The scattering amplitudes are obtained by solving the Lippmann-Schwinger equation.The Belle and BESIII e+e−→Λc+Λˉc− and e+e−→ψ(2S)π+π− cross-sections reveal markedly different pole structures for the ψ(4360). It emerges as a dynamically generated state for the Belle data, whereas it appears as a bare state in the BESIII fit. In contrast, the ψ(4660) pole found on the unphysical Riemann sheet above the Λc+Λˉc− threshold is associated with a bare pole on the real axis in both fits.
@article{arxiv.2605.03320,
title = {Does $\psi(4660)$ exist?},
author = {Xian-Chen Wang and Quanxing Ye and Qian wang},
journal= {arXiv preprint arXiv:2605.03320},
year = {2026}
}