arXiv subjects

Bing-Dong Wan

Publications and source records attributed to Bing-Dong Wan.

At least 19 recordsLinked to original sources

arXiv2026

Discriminating baryonium and final-state-interaction interpretations of $X(2356)$

We revisit the $X(2356)$ enhancement observed by BESIII in $e^+e^-\toΛ\barΛη$ from the viewpoint of near-threshold dynamics. Motivated by the possibility of light $Λ\barΛ$ baryonium, we compare this interpretation with final-state-interaction (FSI) explanations within a minimal FSI-dressed pole framework. Fits of the pure-FSI, baryonium-like-pole, and mixed pole--continuum scenarios to the digitized BESIII spectrum identify the energy-dependent FSI description as providing the best balance between fit quality and model complexity. The extracted pole positions depend strongly on the amplitude parametrization, demonstrating the sensitivity of the baryonium interpretation to the treatment of the continuum. We discuss how decay channels, spin observables, and partner searches can provide complementary constraints on the dynamics underlying the enhancement.

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arXiv2026

Decipher the nature of glueball candidate $X(2370)$

As a unique form of matter composed entirely of gauge bosons, glueballs are an important low-energy prediction of QCD. After decades of searches, the BESIII Collaboration recently suggested that $X(2370)$ may contain a dominant glueball component, based largely on evidence that it is approximately a flavor singlet. Recognizing that flavor-singlet character does not uniquely identify a glueball, we perform a comprehensive analysis using available mass, flavor-singlet, and decay constraints. We find that three flavor-singlet configurations-hybrid meson, tetraquark state, and trigluon glueball-can satisfactorily reproduce the existing experimental data. Among these possibilities, the hybrid structure best describes the measured three-pseudoscalar decay ratios. To ultimately pin down the dominant structure of $X(2370)$, we propose measuring the decay-width ratios $a_0(1450)π/[K_0^*(1430)\bar K+\mathrm{c.c.}]$ and $ϕϕ/[b_1(1235)ρ]$, which can exclusively distinguish these three scenarios.

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arXiv2026

Nodal filtering in open-charm decays of the $ψ(4040)$--$ψ(4160)$ system

Hadronic decay channels can provide direct information on the momentum-space structure of confined quark systems. We investigate this possibility in the $ψ(4040)$--$ψ(4160)$ system using an instantaneous Bethe--Salpeter (BS) framework combined with a relativistic $^3P_0$ decay model. The BS solutions yield nearby bare $3\,^3S_1$ and $2\,^3D_1$ states at 4051 and 4110 MeV, respectively, whose opposite displacements from the physical vector states motivate an effective two-state level-repulsion description. By comparing the matched open-charm channels $D\bar D$, $D\bar D^*+{\rm c.c.}$, $D_s\bar D_s$, and $D_s\bar D_s^*+{\rm c.c.}$ with the same leading $P$-wave threshold behavior, we show that channel-dependent overlap kernels act as momentum-space nodal filters. At $M=4146$ MeV, the $PV/PP$ width ratio is 0.253 in the nonstrange sector but 1.63 in the strange sector, reversing the ordering expected from phase space alone. The momentum-resolved amplitudes reveal that different channels weight opposite sides of the same $2D$ nodal region differently, leading to distinct cancellation patterns and a common recoil condition, $P_f\simeq0.775$ GeV, for charge-resolved $D\bar D^*$ amplitude zeros. These results establish open-charm decays as a probe of momentum-space wave-function structures in heavy quarkonium.

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arXiv2026

QCD sum rule analysis of local meson-meson currents for the $K(1690)$ state

The nature of the recently observed $K(1690)$ state, reported by the COMPASS Collaboration as a candidate strange crypto-exotic meson with $J^P=0^-$, remains unclear. In this work, we investigate whether it can be described by local meson-meson currents within the framework of QCD sum rules. We construct a set of independent local color-singlet meson-meson interpolating currents with $J^P=0^-$ and analyze their QCD sum rules. For the currents that admit reliable Borel windows, the extracted effective mass scales are consistently in the range of $2.0$--$2.3~\mathrm{GeV}$, significantly above the experimental mass of the $K(1690)$. Within the standard pole-plus-continuum framework, none of the selected local currents yields a separately resolved low-lying pole compatible with the COMPASS signal. These results indicate that the selected local color-singlet meson-meson currents do not isolate the $K(1690)$ signal within the present framework, while leaving open the possibility of more extended molecular dynamics and other configurations beyond the present analysis.

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arXiv2026

Finite-Width Dissolution of Radial Spectroscopy in Single-Top Mesonic Correlations

Within the heavy-mass expansion, the pole width of a system containing one unstable heavy constituent inherits the constituent width up to $\mathcal O(Λ_{\rm kin}^2/m_Q^2)$ corrections, while radial splittings remain $\mathcal O(Λ_{\rm rad})$. The top quark is an extreme realization of this hierarchy. We implement the complex top pole mass in an instantaneous Bethe--Salpeter framework, where a biorthogonal Hellmann--Feynman relation realizes width inheritance at the operator level and an artificial heavy-mass scan confirms the predicted $m_Q^{-2}$ suppression. The low-pole source-projected response has a single broad maximum at the physical top width in the $t\bar b$, $t\bar c$, and $t\bar u$ channels. Full width-dependent non-Hermitian re-diagonalization and a direct full-matrix resolvent evaluation confirm the progressive dissolution of the small-width radial maxima. Thus stable-top eigenvalues survive as reference poles but not as a resolvable multi-peak spectrum; they may instead leave qualitative, process-dependent $Wb\bar q$ signatures, such as a broad threshold enhancement or modified color flow.

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arXiv2026

Spectroscopy of hidden-heavy tetraquark states with $J^{PC}=0^{--}$ in a color-octet configuration

Within the QCD sum-rule framework, we investigate hidden-heavy tetraquark channels with the exotic quantum number $J^{PC}=0^{--}$ using four representative local color-octet--octet interpolating currents. The currents include both vector--axialvector and scalar--pseudoscalar Dirac structures. The operator product expansion is carried out up to dimension-eight condensates. The four diagonal sum rules yield mutually consistent mass estimates in the range $10.8$--$11.1~\mathrm{GeV}$ for the hidden-bottom sector and around $4.3$--$4.6~\mathrm{GeV}$ for the corresponding hidden-charm sector, with the bottom sector exhibiting the clearest Borel stability. Since local tetraquark currents with the same quantum numbers are related by Fierz rearrangements, the current-dependent results do not by themselves imply four distinct states or uniquely defined internal color structures. We also discuss quantum-number-allowed decay channels and emphasize the absence of the lowest pseudoscalar--pseudoscalar heavy-meson modes for a neutral $0^{--}$ state. The results provide theoretical guidance for future experimental searches at Belle II, LHCb, and BESIII.

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arXiv2026

SU(3)-flavor breaking as a structural probe of hidden-charm-strange $0^{--}$ tetraquarks in a color-octet basis

We study hidden-charm-strange tetraquark candidates with the exotic quantum number $J^{PC}=0^{--}$ to test whether SU(3)-flavor breaking acts as a universal mass shift or as a structural probe of a fixed color-octet current basis. Using $[\bar c c]_{8_c}\otimes[\bar s s]_{8_c}$-type and $[\bar c s]_{8_c}\otimes[\bar s c]_{8_c}$-type color-octet currents within QCD sum rules, we keep the strange-quark mass and strange condensates explicitly in the operator product expansion through dimension eight so that the strange-sector response can be traced at fixed color and Dirac structure. The hidden-charm-strange system is treated as the primary phenomenological target, while the hidden-bottom-strange sector serves as a stability benchmark. The strange-sector spectrum remains ordered, but the induced charm-sector shifts are grouped rather than uniform, with relatively small shifts for the $[\bar c c]_{8_c}\otimes[\bar s s]_{8_c}$ configurations and substantially larger shifts for the $[\bar c s]_{8_c}\otimes[\bar s c]_{8_c}$ ones. The $[\bar c s]_{8_c}\otimes[\bar s c]_{8_c}$ solutions are shifted toward the $D_s^*\bar D_{s1}$ threshold region, with one overlapping this region within uncertainties and another showing the largest positive SU(3)-breaking shift. Taken together, these features indicate that hidden strangeness can serve as a useful discriminator of internal current structure in the exotic $0^{--}$ sector.

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arXiv2026

The S-wave topped meson

Motivated by the recent near-threshold enhancement in top-quark pair production reported by CMS and ATLAS, we study the S-wave spectral structure of heavy-light systems containing a single top quark, namely $t\bar{q}$, $t\bar{c}$, and $t\bar{b}$, within the instantaneous Bethe-Salpeter formalism. Because the top quark decays on a timescale much shorter than the typical hadronization time, the discrete eigenvalues we obtain should be interpreted as model-dependent reference positions of possible quasi-bound heavy-light configurations, rather than as predictions for fully formed conventional hadrons. The numerical results indicate that the masses of these configurations lie close to the top-quark mass. For the $t\bar{b}$ system, the masses of the first four S-wave $0^{-}$ radial states are about $5.1$, $5.4$, $5.6$, and $5.7$~GeV above the top-quark mass, respectively. For the $t\bar{c}$ system, the corresponding values are about $1.9$, $2.2$, $2.5$, and $2.6$~GeV. We also briefly discuss possible production and decay patterns at a qualitative level, which may serve as a reference for future dedicated phenomenological studies or for experimental constraints.

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arXiv2026

Nodal mechanism for the suppressed $D\bar D$ decay of $ψ(4040)$ in the Bethe--Salpeter framework

The strong decay $ψ(4040)\to D\bar D$ is anomalously suppressed despite ample phase space, whereas the $D\bar D^*$ and $D_s\bar D_s$ channels remain sizable. In this work, we study this suppression and the associated open-charm hierarchy in the framework of the instantaneous Bethe--Salpeter equation combined with the relativistic $^3P_0$ model, with the pair-creation strength fixed independently from $ψ(3770)\to D\bar D$. Within this framework, we show that the suppressed $D\bar D$ mode can be understood as a consequence of node-induced cancellations in the relativistic decay amplitude. The $D\bar D$ amplitude is strongly reduced because the corresponding overlap integral receives comparable positive and negative contributions from different momentum regions, whereas the $D\bar D^*$ and $D_s\bar D_s$ channels do not undergo the same strong cancellation. This interpretation is further supported by the pronounced sensitivity of the $D\bar D$ width to the initial mass, the charged-neutral $D$-meson mass splitting, and the dip structure in the mass dependence of the partial width. Our results provide a dynamical explanation of the suppressed $D\bar D$ mode and the core open-charm hierarchy of $ψ(4040)$ within a conventional $3\,{}^3S_1$ charmonium picture, while the precise value of the near-vanishing $D\bar D$ width remains model dependent.

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arXiv2026

Light baryonium states with exotic quantum numbers

The existence of baryonium-bound or resonant states composed of a baryon and an antibaryon has long been postulated as a natural extension of conventional hadron spectroscopy. In the present work, we conduct a systematic investigation of the mass spectrum and internal configurations of light baryonium candidates exhibiting exotic quantum numbers that are inaccessible within the framework of the traditional quark model. Employing the method of QCD sum rules, we analyze nucleon-antinucleon and light hyperon-anti-hyperon systems with quantum numbers $J^{PC}=0^{--}$ and $0^{+-}$, which are quantum number combinations prohibited for conventional mesonic states. Our analysis reveals the potential existence of two $0^{--}$ $Λ$-$\barΛ$ baryonium states with masses $(2.90\pm0.09)$ GeV and $(3.36\pm0.09)$ GeV, respectively, as well as two $0^{+-}$ $Λ$-$\barΛ$ states with masses $(2.91\pm0.07)$ GeV and $(3.29\pm0.07)$ GeV, respectively. In addition, corresponding nucleon-antinucleon partner states are identified at $(2.69\pm0.07)$ GeV, $(3.07\pm0.08)$ GeV, $(2.86\pm0.07)$ GeV, and $(3.22\pm0.07)$ GeV, respectively. Furthermore, analogous $Ξ$-$\barΞ$ configurations are predicted with masses of $(3.10\pm0.09)$ GeV, $(3.54\pm0.07)$ GeV, $(3.08\pm0.08)$ GeV, and $(3.45\pm0.08)$ GeV, respectively. The possible decay modes of the light exotic baryonium states are analyzed, which are hopefully measurable in BESIII, BELLEII, and LHCb experiments.

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arXiv2026

Spectrum of $J^{PC} = 0^{\pm\pm}$ Gluonic Hidden-Charm Tetraquark States

We investigate gluonic hidden-charm tetraquark states composed of two valence quarks, two valence antiquarks and an explicit valence gluon. In the color configuration $[\bar{3}_c]_{c q}\otimes[8_c]_{G}\otimes[3_c]_{\bar{c}\bar{q}}$, a complete set of eight interpolating currents is constructed for states with quantum numbers $^{PC}=0^{++}$, $0^{-+},$ $0^{--}$, and $0^{+-}$. The corresponding mass spectra are systematically analysed within the QCD sum rule framework, including nonperturbative condensate contributions up to dimension eight. Our numerical analysis indicates the possible existence of six gluonic hidden-charm tetraquark states exhibiting stable behaviour in the adopted Borel windows. By replacing the charm quark with the bottom quark, masses for the corresponding hidden-bottom partners are also estimated. Possible production mechanisms and dominant decay channels are discussed, providing phenomenological guidance for experimental searches. These predicted states may be accessible at current and forthcoming facilities, including Belle II, PANDA, SuperB and LHCb, and thus offer an opportunity to probe explicit gluonic degrees of freedom in multiquark systems and deepen our understanding of nonperturbative QCD.

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arXiv2026

Hidden-charm and -bottom tetraquark states with $J^{PC}=1^{-+}$ via QCD sum rules

We investigate the $1^{-+}$ hidden-charm and hidden-bottom tetraquark states within the framework of QCD sum rules. The mass spectra are computed by including condensates up to dimension eight in the operator product expansion. Our results indicate the possible existence of four $1^{-+}$ hidden-charm tetraquark states, with predicted masses of $(4.83 \pm 0.15)$ GeV, $(4.88 \pm 0.18)$ GeV, $(4.72 \pm 0.16)$ GeV, and $(4.79 \pm 0.12)$ GeV, while their hidden-bottom counterparts are estimated to have masses of $(11.08 \pm 0.16)$ GeV, $(11.16 \pm 0.14)$ GeV, $(10.99 \pm 0.16)$ GeV, and $(11.03 \pm 0.15)$ GeV, respectively. We also analyze the possible decay modes of these tetraquark states, which may be accessible in future experiments at BESIII, Belle~II, LHCb, and future STCF. These findings provide valuable guidance for the experimental search for exotic $1^{-+}$ tetraquark states in both the charm and bottom sectors.

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arXiv2025

Fully strange tetraquark states via QCD sum rules

In this paper, we have systematically explored the mass spectrum of fully strange tetraquark candidates within the framework of QCD sum rules, focusing on states with quantum numbers $J^{PC}=0^{++}$, $0^{-+}$, $0^{--}$, $1^{--}$, $1^{+-}$, and $1^{++}$. The analysis reveals the existence of fully strange tetraquark states with masses ranging from approximately $2.07$ to $3.12$ GeV. These predictions are confronted with existing experimental observations of potential fully strange tetraquark resonances, notably the $X(2300)$ recently reported by the BESIII Collaboration, which may be interpreted as a fully strange tetraquark state. Furthermore, the possible decay modes of these fully strange tetraquark states are analyzed, providing guidance for their identification in current and future high energy experiments such as BESIII, Belle II, and LHCb.

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arXiv2025

Mass spectrum of the $Ω\barΩ$ states

In this study, we investigate the mass spectrum of the $Ω\barΩ$ states with quantum numbers $J^{PC}=0^{-+}$, $1^{--}$, $0^{++}$, and $1^{++}$ within the framework of QCD sum rules. Employing suitably constructed interpolating currents, the analyses are carried out with the operator product expansion (OPE) including condensate contributions up to dimension $12$. Our results indicate the existence of four possible baryonium states with masses $m_{0^{-+}}=(3.22\pm0.07)$ GeV, $m_{1^{--}}=(3.28\pm0.08)$ GeV, $m_{0^{++}}=(3.46\pm0.09)$ GeV, and $m_{1^{++}}=(3.54\pm0.11)$ GeV. For the $0^{-+}$ and $1^{--}$ states, the predicted masses lie below the corresponding dibaryon thresholds, suggesting possible bound-state configurations. In contrast, the $0^{++}$ and $1^{++}$ states are found above the respective thresholds, implying resonance-like behavior. Potential decay channels for these baryonium candidates are discussed, with emphasis on those accessible to current experimental facilities such as BESIII, Belle II, and LHCb.

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arXiv2025

Gluonic Hidden-charm Tetraquark States

In this paper, a new type of hybrid state, which consists of two valence quarks and two valence antiquarks together with a valence gluon, the gluonic tetraquark states, are investigated. Twenty-four currents of the the gluonic hidden-charm tetraquark states in $[\bar{3}_c]_{c q}\otimes[8_c]_{G}\otimes[3_c]_{\bar{c} \bar{q^\prime}}$ configuration are constructed, and their mass spectrum are evaluated in the framework of QCD sum rules with quantum numbers of $J^P=0^{+}$, $0^{-}$, $1^{-}$, and $1^{+}$. The nonperturbative contributions up to dimension 8 are taken into account. The results indicate that there may be exist 14 gluonic hidden-charm tetraquark states, and their corresponding hidden-bottom partners are also evaluated. The possible production and decay modes of the gluonic tetraquark states are analyzed, which are hopefully measurable in BESIII, BELLEII, PANDA, Super-B, and LHCb experiments.

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arXiv2024

Mass spectra of $0^{--}$ and $0^{+-}$ hidden-heavy baryoniums

In this work, the spectra of the prospective exotic hidden-charm and hidden-bottom baryonium, viz. the baryon-antibaryon states, with $J^{PC}=0^{--}$ and $0^{+-}$ are investigated in the framework of QCD sum rules. The non-perturbative contributions up to dimension 12 are taken into account. Numerical results indicate that there might exist 3 possible $0^{--}$ hidden-charm baryonium states with masses $(5.22\pm0.26)$, $(5.52\pm0.25)$, and $(5.46\pm0.24)$ GeV, and 5 possible $0^{+-}$ hidden-charm baryonium states with masses $(4.76\pm0.28)$, $(5.24\pm0.28)$, $(5.16\pm0.27)$, $(5.52\pm0.27)$, and $(5.69\pm0.27)$ GeV, respectively. The corresponding hidden-bottom partners are found lying in the range of $11.68-12.28$ GeV and $11.38-12.33$ GeV, respectively. The possible baryonium decay modes are analyzed, which are hopefully measurable in LHC experiments.

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arXiv2022

Gluonic nature of the newly observed state $X(2600)$

Motivated by the newly observed resonance $X(2600)$ by BESIII Collaboration, we examine the trigluon glueball interpretation for it in the framework of QCD sum rules. We evaluate the mass spectra of the trigluon glueballs with quantum numbers $0^{-+}$ and $2^{-+}$ up to dimension 8 condensate in the operator product expansion. Our numerical results indicate that the mass of the $2^{-+}$ trigluon glueball is about $2.66\pm 0.06$ GeV, which is consistent with the mass of the X(2600) within the uncertainties, while $0^{-+}$ has a mass of $2.01\pm0.14$ GeV. The possible decay channels of the $2^{-+}$ state are analyzed, which are crucial in decoding $X(2600)$'s internal structure and are hopefully measurable in BESIII, BEllEII, PANDA, and LHCb experiments.

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arXiv2022

Possible structure of the newly found exotic state $η_1(1855)$

Recently, a hadronic state named $η_1(1855)$, about 1.86 GeV, was observed in the BESIII experiment. This finding has a peculiar interest due to its exotic quantum number $J^{PC}=1^{-+}$. In this paper, we examine the tetraquark interpretation for the structure of $η_1(1855)$ in the configurations of $[1_c]_{\bar{s}s}\otimes[1_c]_{\bar{q}q}$ and $[1_c]_{\bar{s}q}\otimes[1_c]_{\bar{s}q}$, and perform a mass spectrum calculation in the framework of QCD sum rules. The results show that the observed $η_1(1855)$ could be embedded into the $[1_c]_{\bar{s}s}\otimes[1_c]_{\bar{q}q}$ configuration. The possible tetraquark and hybrid decay modes are analyzed, which are critical in decoding its inner structure. In the same way, we evaluate as well the $\bar{s}s\bar{s}s$ molecular state with $1^{-+}$ quantum number and find that there might exist two such ground states.

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