Vector charmonium(-like) states in the energy range of 4.1-4.6 GeV
Abstract
The spectrum of vector charmonium(-like) states in the 4.1\dash4.6~GeV energy region exhibits a long-standing tension between inclusive and exclusive measurements. While the inclusive R-value indicates only conventional vector charmonia such as ψ(4160) and ψ(4415), exclusive e+e- cross sections reveal additional structures whose parameters strongly depend on the observed final states when fitted with Breit--Wigner functions. This puzzling pattern suggests that coupled-channel and threshold effects play an essential role. In this work, we develop a unified coupled-channel framework for the 1−− resonances in this energy region. The framework incorporates the S-wave open-charm channels DD̅1, D*D̅1, and D*D̅2* constrained by heavy-quark spin symmetry, optional bare poles associated with ψ(4160) and ψ(4415), and final-state interactions in the Zc channels. We perform simultaneous fits to the BESIII cross sections for e+e-→ J/ψπ+π-, hcπ+π-, DD̅*π, D*D̅*π, J/ψη, and χc0ω, together with invariant-mass distributions exhibiting the Zc(3900) and Zc(4020) structures. The benchmark models differ in the number of bare seed states and the fitting strategy. We show that even the purely dynamical scheme without bare charmonia captures the gross features of the analyzed distributions. The inclusion of bare compact states improves the fit quality but does not change the conclusion that the measured line shapes can be understood in terms of strong coupled-channel effects with dynamically generated poles. We also discuss possible heavy-quark spin partners of the exotic 1−− states.
Versions
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BibTeX
@misc{dong2026vector,
title = {{Vector charmonium(-like) states in the energy range of 4.1-4.6 GeV}},
author = {Xiang-Kun Dong and Vadim Baru and Leon von Detten and Feng-Kun Guo and Christoph Hanhart and Teng Ji and Ulf-G. Meißner and Alexey Nefediev},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.06180},
eprint = {2606.06180},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.06180},
}
RIS
TY - UNPB
TI - Vector charmonium(-like) states in the energy range of 4.1-4.6 GeV
AU - Xiang-Kun Dong
AU - Vadim Baru
AU - Leon von Detten
AU - Feng-Kun Guo
AU - Christoph Hanhart
AU - Teng Ji
AU - Ulf-G. Meißner
AU - Alexey Nefediev
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2606.06180
UR - https://arxiv.org/abs/2606.06180
AB - The spectrum of vector charmonium(-like) states in the 4.1\dash4.6~GeV energy region exhibits a long-standing tension between inclusive and exclusive measurements. While the inclusive R-value indicates only conventional vector charmonia such as ψ(4160) and ψ(4415), exclusive e^+e^- cross sections reveal additional structures whose parameters strongly depend on the observed final states when fitted with Breit--Wigner functions. This puzzling pattern suggests that coupled-channel and threshold effects play an essential role. In this work, we develop a unified coupled-channel framework for the 1^−− resonances in this energy region. The framework incorporates the S-wave open-charm channels DD̅_1, D^*D̅_1, and D^*D̅_2^* constrained by heavy-quark spin symmetry, optional bare poles associated with ψ(4160) and ψ(4415), and final-state interactions in the Z_c channels. We perform simultaneous fits to the BESIII cross sections for e^+e^-→ J/ψπ^+π^-, h_cπ^+π^-, DD̅^*π, D^*D̅^*π, J/ψη, and χ_c0ω, together with invariant-mass distributions exhibiting the Z_c(3900) and Z_c(4020) structures. The benchmark models differ in the number of bare seed states and the fitting strategy. We show that even the purely dynamical scheme without bare charmonia captures the gross features of the analyzed distributions. The inclusion of bare compact states improves the fit quality but does not change the conclusion that the measured line shapes can be understood in terms of strong coupled-channel effects with dynamically generated poles. We also discuss possible heavy-quark spin partners of the exotic 1^−− states.
ER -