arXiv subjects

Zi-Long Man

Publications and source records attributed to Zi-Long Man.

11 recordsLinked to original sources

arXiv2026

$T^a_{c\bar{s}0}(2900)$, $T_{cs0}^*(2900)^0$, and other singly heavy tetraquark states

We systematically study the mass spectra of $S$-wave singly heavy tetraquark states $Qq\bar{q}\bar{q}$ ($Q=c,b$; $q=u,d,s$) in a mass splitting model. We adopt the assumption that the $X(4140)$ is the lowest $J^{PC}=1^{++}$ $cs\bar{c}\bar{s}$ tetraquark and use this state as a reference to determine the mass splittings. According to the obtained results, we also estimate the rearrangement decay widths of the tetraquarks within a simple scheme. We find that the recently observed states $T^a_{c\bar{s}0}(2900)^{++/0}$ and $T_{cs0}^*(2900)^0$ by the LHCb Collaboration can be consistently interpreted as the second highest $I(J^P)=1(0^+)$ $cn\bar{s}\bar{n}$ ($n=u,d$) and the higher $I(J^P)=0(0^+)$ $cs\bar{n}\bar{n}$ tetraquark states, respectively. We predict several narrow tetraquark candidates: the lowest $cn\bar{s}\bar{n}$ and $cs\bar{n}\bar{n}$ with $I(J^P)=0(0^+)$ and $0(1^+)$, and their bottom counterparts. The obtained information from mass spectrum and rearrangement decay properties will help search for the new singly heavy tetraquark states.

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arXiv2026

Proposed mixing between $2P$ and $1F$ wave charmonia

We investigate $2P$-$1F$ mixing in charmonium, focusing on the close-in-mass $\chi_{c2}(2P)$ and $\chi_{c2}(1F)$ states. The conventional tensor force yields negligible mixing, motivating the inclusion of coupled-channel effects. Our unquenched calculation reveals sizable mixing angles of $7.5^\circ$ and $15.4^\circ$. We predict the corresponding two-photon and two-gluon decay widths as key observables for experimental verification. Additionally, we discuss the production of these two $2P$-$1F$ mixed states of charmonium via $\gamma\gamma$ fusion. Current data are insufficient to determine the mixing, highlighting the need for precise future measurements to resolve this aspect of charmonium spectroscopy.

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arXiv2026

Assessing the validity of the Born-Oppenheimer approximation in potential models for doubly heavy hadrons

The Born-Oppenheimer approximation is widely used to investigate the properties of hydrogen-like systems and doubly heavy hadrons. However, the extent to which this approximation captures the features of such systems within potential models remains an open question. In this work, we adopt the results obtained with the Gaussian expansion method as a benchmark to assess the validity of the Born-Oppenheimer approximation within potential models for hadronic systems. We also investigate the dependence of the Born-Oppenheimer approximation results on the choice of trial wave functions. A comprehensive study of the Born-Oppenheimer approximation is carried out by performing calculations using Slater-type functions and Gaussian-type functions as trial wave functions, and by comparing the resulting predictions with those obtained from the Gaussian expansion method. We find that the calculations performed within the Born-Oppenheimer approximation are close to those obtained with the Gaussian expansion method when the heavy-quark mass is relatively small. However, as the heavy-quark mass increases, calculations employing Slater-type functions yield larger values than those from the Gaussian expansion method, whereas those using Gaussian-type functions lead to smaller ones. The use of Slater-type functions generally leads to an enhanced binding energy. The underestimation observed in Born-Oppenheimer approximation calculations with Gaussian-type functions primarily stems from the neglect of non-adiabatic corrections. This comparative study provides deeper insight into the structure of doubly heavy hadrons and helps clarify the applicability and limitations of the Born-Oppenheimer treatment within potential models.

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arXiv2025

Is the $3S$-$2D$ mixing strong for the charmonia $\psi(4040)$ and $\psi(4160)$?

In this work, we revisit the $3S$-$2D$ mixing scheme for the charmonia $\psi(4040)$ and $\psi(4160)$. We introduce a coupled-channel mechanism-distinct from the tensor-force contribution in potential models, which alone is insufficient to induce significant mixing-to describe the mixing between these states. Our analysis yields mixing angles of $\theta_1=7^\circ$ and $\theta_2=10^\circ$, inconsistent with the larger angle inferred from experimental data, such as the dilectronic widths of the $\psi(4040)$ and $\psi(4160)$. We discuss possible origins of this discrepancy and emphasize the need for future experiments to resolve it. Precise measurements of the resonance parameters and dilectronic decay widths, via both inclusive and exclusive processes, will be crucial in clarifying this issue.

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arXiv2025

Coupled-channel study of $4S$-$3D$ mixing dynamics in $\psi(4220)$ and $\psi(4380)$

Among charmoniumlike $XYZ$ states, the $\psi(4220)$ and $\psi(4380)$ states have emerged as key candidates for exploring the charmonium spectrum. In this work, we propose a $4S$-$3D$ charmonium mixing scheme for the $\psi(4220)$ and $\psi(4380)$, induced by coupled-channel effects. By constructing a coupled-channel model, we identify the dynamical mechanism responsible for the large mixing angle observed in previous studies, which cannot be explained by conventional potential models alone. Our analysis reveals that the $DD_1$ channel significantly influences the lower state ($\psi(4220)$), while the $D^*D_1$ channel primarily affects the higher state ($\psi(4380)$). Furthermore, we investigate the two-body Okubo-Zweig-Iizuka (OZI)-allowed strong decay behaviors of these states, providing insights into their total widths. This study not only supports the $4S$-$3D$ mixing scheme but also offers a deeper understanding of the role of coupled channels in shaping the charmonium spectrum above 4 GeV. Our results align with experimental observations and provide a framework for interpreting future data on charmonium states.

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arXiv2025

Triply heavy tetraquark states in a mass-splitting model

In a modified chromomagnetic interaction model, assuming $X(4140)$ to be the lowest $1^{++}$ $cs\bar{c}\bar{s}$ tetraquark and treating it as the reference state, we systematically investigated the masses of the triply-heavy tetraquark states $QQ\bar{Q}\bar{q}$ ($Q=c,b;q=u,d,s$). Because of their higher masses, no stable tetraquarks were found. Using a simple scheme, we also estimated the partial widths of the rearrangement decay channels and relevant ratios. A compact triply heavy tetraquark candidate would be favored if its observed mass and partial width ratios were comparable with our predictions. We hope that the present work will be helpful for further studies.

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arXiv2024

Prospects for observing the missing $2D$ and $1F$ charmonium states around 4 GeV

Our understanding of high-lying states within the charmonium family remains incomplete, particularly in light of recent observations of charmonium states at energies around 4 GeV. In this study, we investigate the spectroscopic properties of several high-lying charmonia, focusing on the $2D$ and $1F$ states. A mass spectrum analysis is conducted, incorporating the unquenched effects. We then present a detailed study of the strong decay properties, including partial decay widths for two-body strong decays permitted by the Okubo-Zweig-Iizuka (OZI) rule. Additionally, we explore the primary radiative decay channels associated with these states. Finally, we discuss the radiative transitions of the $2D$ and $1F$ states via $e^+e^-$ annihilation. Theoretical predictions provided here aim to guide future experimental searches for high-lying charmonium states at facilities such as BESIII, Belle II, LHCb, and the future STCF.

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arXiv2024

Charmonium states in a coupled-channel model

We systematically investigate the mass spectrum and two-body open-charm strong decays of charmonium states in a coupled-channel model where the $^3P_0$ quark-antiquark pair creation mechanism is employed. The results of masses, mass shifts, proportions of the $c\bar{c}$ component, and open-charm decay widths are provided. The $S$-$D$ wave mixing angles and di-electric decay widths for vector mesons are also presented. Based on our results, we find that the $\psi(3770)$, $\psi(4040)$, $\psi(4160)$, $\psi(4360)$, and $\psi(4415)$ can be assigned as the $1^3D_1$-, $3^3S_1$-, $2^3D_1$-, $4^3S_1$-, and $3^3D_1$-dominated charmonium states, respectively. The $\psi_3(3842)$ is a good candidate of the $\psi_3(1D)$ charmonium state. The calculated mass and strong decay width of $\chi_{c1}(2P)$ with significant continuum contribution ($\sim$57\%) favor the charmonium interpretation for the mysterious $\chi_{c1}(3872)$. When considering the large uncertainty in the observed decay width, the possibility to assign the $\chi_{c0}(3860)$ as the $\chi_{c0}(2P)$ charmonium state cannot be ruled out. One may describe well the properties of $\chi_{c2}(3930)$ with the $\chi_{c2}(2P)$ charmonium. The predictions on properties of other $c\bar{c}$ states can be tested by future experiments.

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arXiv2023

Doubly heavy tetraquark states in a mass splitting model

Treating the $X(4140)$ as a compact $J^{PC}=1^{++}$ $cs\bar{c}\bar{s}$ state and using its mass as a reference scale, we systematically estimate the masses of doubly heavy tetraquark states $QQ\bar{q}\bar{q}$ where $Q=c,b$ and $q=u,d,s$. Their decay properties are studied with a simple rearrangement scheme. Based on our results, the lowest $I(J^P)=0(1^+)$ $bb\bar{n}\bar{n}$ state is a stable tetraquark about 20 MeV below the $\bar{B}^*\bar{B}$ threshold. The mass and width of the low-mass $0(1^+)$ $cc\bar{n}\bar{n}$ ($n=u,d$) tetraquark are compatible with the $T_{cc}(3875)^+$ observed by the LHCb Collaboration. The location of the lowest $0(0^+)$ and $0(1^+)$ $bc\bar{n}\bar{n}$ states are found to be close to the $\bar{B}D$ and $\bar{B}^*D$ thresholds, respectively. We hope that the predicted ratios between partial widths of different channels may be helpful to identify compact tetraquark states from future measurements.

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arXiv2023

$X(3960)$, $X_0(4140)$, and other compact $cs\bar{c}\bar{s}$ states

We study the spectrum and rearrangement decays of S-wave $cs\bar{c}\bar{s}$ tetraquark states in a simplified quark model. The masses and widths are estimated by assuming that the $X(4140)$ is the lower $1^{++}$ $cs\bar{c}\bar{s}$ tetraquark. Comparing our results with experimental measurements, we find that the recently observed $X(3960)$ by LHCb can be assigned as the lowest $0^{++}$ $cs\bar{c}\bar{s}$ tetraquark state and the $X_0(4140)$ could be the second lowest $0^{++}$ $cs\bar{c}\bar{s}$ tetraquark. Predictions of ratios between partial widths for the involved tetraquarks are given. We call for searches for more $cs\bar{c}\bar{s}$ tetraquarks with $J^{PC}=1^{+-}$, $0^{++}$, and $2^{++}$.

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arXiv2023

Hidden-charm pentaquark states in a mass splitting model

Assuming that the $P_c(4312)^+$ is a $I(J^P)=\frac12(\frac32^-)$ compact pentaquark, we study the mass spectrum of its S-wave hidden-charm partner states in a color-magnetic interaction model. Combining the information from their decays obtained in a simple rearrangement scheme, one finds that the quantum numbers of $P_c(4457)^+$, $ P_c(4440)^+$, and $P_c(4337)^+$ can be assigned to be $I(J^P)=\frac12(\frac32^-)$, $\frac12(\frac12^-)$, and $\frac12(\frac12^-)$, respectively, while both $P_{cs}(4338)^0$ and $P_{cs}(4459)^0$ can be interpreted as $I(J^P)=0(\frac12^-)$ $udsc\bar{c}$ compact states. Based on the numerical results, we also find narrow pentaquarks in $ssnc\bar{c}$ ($n=u,d$) and $sssc\bar{c}$ systems. The decay properties of the studied pentaquarks and the searching channels for them can be tested in future experiments.

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