A toy model for hadronic bonds in exotic hadrons
Abstract
Three hadronic-bond mechanisms were proposed in our previous studies to describe near-threshold exotic hadrons in terms of hadronic molecular configurations: the covalent bond arises from the sharing and exchange of valence light quarks between hadronic clusters, the creation bond originates from the activation of coherent sea qq̅ degrees of freedom followed by the formation of effective covalent correlations, and the annihilation bond arises from valence qq̅ annihilation and the associated mixing with a nearby compact state. A simple toy model was previously constructed only for the covalent bond, and in the present study we extend this model to incorporate the creation and annihilation bonds within a unified framework. The resulting framework organizes covalent-bond configurations as tending to lie below threshold and creation-bond configurations as tending to appear above threshold, while the annihilation bond can shift a pre-existing molecular configuration either downward or upward through mixing with a nearby compact state. An effective activation energy Eact is introduced for the coherent sea four-quark component involved in the creation bond, with the Zc(3900) providing the benchmark value Eact∼17 MeV. Intriguingly, this value is numerically close to the reported mass of the X17 particle, which we previously interpreted as a low-energy bare four-quark structure. This numerical proximity may therefore reflect common low-energy (four-quark) dynamics, although the microscopic connection remains to be established. For the isoscalar D*D̅*B*B̅* configuration involving the Zc(4020) and Zb(10650) creation-bond subsystems linked by two additional covalent bonds, we estimate a binding energy of approximately 36 MeV below its four-meson threshold and propose searches in the 4μ and 4μ2π final states.
Related
- Exotic hadrons associated with b-quark
- Compositeness of near-threshold exotic hadrons in systems with Coulomb and short-range interactions
- Instanton liquid framework for non-perturbative QCD in light hadrons
- When hadrons collide: di-J/psi structure in the final state
- From a Long-standing Prediction to a New Family of Hadrons
BibTeX
@misc{chen2026model,
title = {{A toy model for hadronic bonds in exotic hadrons}},
author = {Hua-Xing Chen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.15436},
eprint = {2610.15436},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.15436},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A toy model for hadronic bonds in exotic hadrons
AU - Hua-Xing Chen
PY - 2026
DA - 2026/10/11
PB - arXiv
DO - 10.48550/arxiv.2610.15436
UR - https://arxiv.org/abs/2610.15436
AB - Three hadronic-bond mechanisms were proposed in our previous studies to describe near-threshold exotic hadrons in terms of hadronic molecular configurations: the covalent bond arises from the sharing and exchange of valence light quarks between hadronic clusters, the creation bond originates from the activation of coherent sea qq̅ degrees of freedom followed by the formation of effective covalent correlations, and the annihilation bond arises from valence qq̅ annihilation and the associated mixing with a nearby compact state. A simple toy model was previously constructed only for the covalent bond, and in the present study we extend this model to incorporate the creation and annihilation bonds within a unified framework. The resulting framework organizes covalent-bond configurations as tending to lie below threshold and creation-bond configurations as tending to appear above threshold, while the annihilation bond can shift a pre-existing molecular configuration either downward or upward through mixing with a nearby compact state. An effective activation energy E_act is introduced for the coherent sea four-quark component involved in the creation bond, with the Z_c(3900) providing the benchmark value E_act∼17 MeV. Intriguingly, this value is numerically close to the reported mass of the X_17 particle, which we previously interpreted as a low-energy bare four-quark structure. This numerical proximity may therefore reflect common low-energy (four-quark) dynamics, although the microscopic connection remains to be established. For the isoscalar D^*D̅^*B^*B̅^* configuration involving the Z_c(4020) and Z_b(10650) creation-bond subsystems linked by two additional covalent bonds, we estimate a binding energy of approximately 36 MeV below its four-meson threshold and propose searches in the 4μ and 4μ2π final states.
ER -