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Wei-Zhen Deng

Publications and source records attributed to Wei-Zhen Deng.

At least 19 recordsLinked to original sources
arXiv2024

Heavy baryons in the relativized quark model with chromodynamics

Following the work of Capstick and Isgur [\href{https://doi.org/10.1103/PhysRevD.34.2809}{Phys.~Rev.~D~34,~2809~(1986)}], we systematically study the mass spectrum of the heavy baryons in the relativized quark potential model with chromodynamics. Besides the original Godfrey-Isgur (GI) model, we also adopt a modified GI model which replaces the linear confinement by a screened one. The two models give similar results in our work. All heavy baryons observed so far can be explained as three-quark states. In particular, we identify the $Ω_{c}(3000)$/$Ω_{b}(6316)$, $Ω_{c}(3050)$/$Ω_{b}(6330)$, $Ω_{c}(3065)$/$Ω_{b}(6340)$ and $Ω_{c}(3090)$/$Ω_{b}(6350)$ states as the $p_λ$ excitations with quantum numbers $1/2^{-}$, $3/2^{-}$, $3/2^{-}$ and $5/2^{-}$. The $Ω_{c}(3120)$ is a $3/2^{-}$ state with the $p_ρ$ excitation, whose bottom partner is predicted to be $Ω_{b}(6446/6457,3/2^{-})$. The higher state $Ω_{c}(3188)$ is the $2s_λ$ excitation with quantum numbers $1/2^{+}$, and $Ω_{c}(3327)$ is a $d_λ$ excitation with quantum numbers $3/2^{+}$ or $5/2^{+}$. In addition, the $Λ_{c}(2940)$ with quantum numbers $J^{P}=3/2^{-}$ could be explained as the $p_ρ$ excitation.

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arXiv2022

Triply heavy tetraquark states

In the framework of an extended chromomagnetic model, we systematically study the mass spectrum of the $S$-wave $qQ\bar{Q}\bar{Q}$ tetraquarks. Their mass spectra are mainly determined by the color interaction. For the $qc\bar{c}\bar{c}$, $qb\bar{c}\bar{c}$ and $qb\bar{b}\bar{b}$ tetraquarks, the color interaction favors the color-sextet $\ket{(qQ)^{6_{c}}(\bar{Q}\bar{Q})^{\bar{6}_{c}}}$ configuration over the color-triplet $\ket{(qQ)^{\bar{3}_{c}}(\bar{Q}\bar{Q})^{3_{c}}}$ one. But for the $qc\bar{b}\bar{b}$ tetraquarks, the color-triplet configuration is favored. We find no stable states which lie below the thresholds of two pseudoscalar mesons. The lowest axial-vector states with the $qQ\bar{b}\bar{b}$ flavor configuration may be narrow. They lie just above the thresholds of two pseudoscalar mesons, but cannot decay into these channels because of the conservation of the angular momentum and parity.

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arXiv2021

Doubly heavy tetraquarks in an extended chromomagnetic model

Using an extended chromomagnetic model, we perform a systematic study of the masses of the doubly heavy tetraquarks. We find that the ground states of the doubly heavy tetraquarks are dominated by color-triplet $\ket{(qq)^{\bar{3}_{c}}(\bar{Q}\bar{Q})^{3_{c}}}$ configuration, which is opposite to that of the fully heavy tetraquarks. The combined results suggest that the color-triplet configuration becomes more important when the mass difference between the quarks and antiquarks increases. We find three stable states which lie below the thresholds of two pseudoscalar mesons. They are the $IJ^{P}=01^{+}$ $nn\bar{b}\bar{b}$ tetraquark, the $IJ^{P}=00^{+}$ $nn\bar{c}\bar{b}$ tetraquark and the $J^{P}=1^{+}$ $ns\bar{b}\bar{b}$ tetraquark.

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arXiv2021

Systematics of fully heavy tetraquarks

In this work, we systematically study the mass spectrum of the fully heavy tetraquark in an extended chromomagnetic model, which includes both color and chromomagnetic interactions. Numerical results indicate that the energy level is mainly determined by the color interaction, which favors the color-sextet $\ket{(QQ)^{6_{c}}(\bar{Q}\bar{Q})^{\bar{6}_{c}}}$ configuration over the color-triplet $\ket{(QQ)^{\bar{3}_{c}}(\bar{Q}\bar{Q})^{3_{c}}}$ one. The chromomagnetic interaction mixes the two color configurations and gives small splitting. The ground state is always dominated by the color-sextet configuration. We find no stable state below the lowest heavy quarkonium pair thresholds. Most states may be wide since they have at least one $S$-wave decay channel into two $S$-wave mesons. One possible narrow state is the $1^{+}$ $bb\bar{b}\bar{c}$ state with a mass $15719.1~\text{MeV}$. It is just above the $η_{b}\bar{B}_{c}$ threshold. But this channel is forbidden because of the conservation of the angular momentum and parity.

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arXiv2021

The magnetic moments and electromagnetic form factors of the decuplet baryons in chiral perturbation theory

We have systematically investigated the magnetic moments and magnetic form factors of the decuplet baryons to the next-to-next-leading order in the framework of the heavy baryon chiral perturbation theory. Our calculation includes the contributions from both the intermediate decuplet and octet baryon states in the loops. We also calculate the charge and magnetic dipole form factors of the decuplet baryons. Our results may be useful to the chiral extrapolation of the lattice simulations of the decuplet electromagnetic properties.

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arXiv2019

Three body open flavor decays of higher vector charmonium and bottomonium

With an extended quark pair creation model we systematically study the OZI-allowed three body open flavor decays of higher vector charmonium and bottomonium states. We obtain that the $BB^*π$ and $B^*B^*π$ partial decay widths of $Υ(10860)$ are consistent with experiment, and the corresponding partial decay widths of $Υ(11020)$ can reach up to 2$\sim$3 MeV. Meanwhile the partial widths of $DD^*π$ and $D^*D^*π$ modes for most higher vector charmonium states can reach up to several MeV.

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arXiv2019

The strong decay patterns of $Z_c$ and $Z_b$ states in the relativized quark model

Employing the relativized quark model and the quark-interchange model, we investigate the decay of the charged heavy quarkonium-like states $Z_c(3900)$, $Z_c(4020)$, $Z_c(4430)$, $Z_b(10610)$ and $Z_b(10650)$ into the ground and radially excited heavy quarkonia via emitting a pion meson. The $Z_c$ and $Z_b$ states are assumed to be hadronic molecules composed of open-flavor heavy mesons. The calculated decay ratios can be compared with the experimental data, which are useful in judging whether the molecule state assignment for the corresponding $Z_c$ or $Z_b$ state is reasonable or not. The theoretical framework constructed in this work will be helpful in revealing the underlying structures of some exotic hadrons.

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arXiv2019

Hidden-charm pentaquarks and $P_c$ states

Recently, the LHCb Collaboration reported three $P_c$ states in the ${J/ψ}p$ channel. We systematically study the mass spectrum of the hidden charm pentaquark in the framework of an extended chromomagnetic model. For the $nnnc\bar{c}$ pentaquark with $I=1/2$, we find that (i) the lowest state is $P_{c}(4327.0,1/2,1/2^{-})$ [We use $P_{c}(m,I,J^{P})$ to denote the $nnnc\bar{c}$ pentaquark], which corresponds to the $P_{c}(4312)$. Its dominant decay mode is $Λ_{c}\bar{D}^{*}$. (ii) We find two states in the vicinity of $P_{c}(4380)$. The first one is $P_{c}(4367.4,1/2,3/2^{-})$ and decays dominantly to $N{J/ψ}$ and $Λ_{c}\bar{D}^{*}$. The other one is $P_{c}(4372.4,1/2,1/2^{-})$. Its dominant decay mode is $Λ_{c}\bar{D}$, and its partial decay width of $Nη_{c}$ channel is comparable to that of $N{J/ψ}$. (iii) In higher mass region, we find $P_{c}(4476.3,1/2,3/2^{-})$ and $P_{c}(4480.9,1/2,1/2^{-})$, which correspond to $P_{c}(4440)$ and $P_{c}(4457)$. In the open charm channels, both of them decay dominantly to the $Λ_{c}\bar{D}^{*}$. (iv) We predict two states above $4.5~\text{GeV}$, namely $P_{c}(4524.5,1/2,3/2^{-})$ and $P_{c}(4546.0,1/2,5/2^{-})$. The masses of the $nnnc\bar{c}$ state with $I=3/2$ are all over $4.6~\text{GeV}$. Moreover, we use the model to explore the $nnsc\bar{c}$, $ssnc\bar{c}$ and $sssc\bar{c}$ pentaquark states.

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arXiv2019

Three body open flavor decays of higher charmonium and bottomonium

In the present work, we study the OZI-allowed three body open flavor decay properties of higher vector charmonium and bottomonium states with an extended quark pair creation model. For the bottomonium system, we get that (i) the $BBπ$ and $B^*B^*π$ partial decay widths of the $Υ(5S)$ state are consistent with the experiment, and the $BB^*π$ partial decay width of the $Υ(5S)$ state is smaller but very close to the Belle's experiment. Meanwhile, (ii) the $BB^*π$ and $B^*B^*π$ decay widths of $Υ(11020)$ can reachs $2\sim3$ MeV. In addition, (iii) for the most of higher vector charmonium states, the partial decay widths of the $DD^*π$ and $D^*D^*π$ modes can reach up to several MeV, which may be observed in future experiments.

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arXiv2018

Masses of doubly heavy-quark baryons in an extended chromomagnetic model

We extend the chromomagnetic model by further considering the effect of color interaction. The effective mass parameters between quark pairs ($m_{qq}$ or $m_{q\bar{q}}$) are introduced to account both the effective quark masses and the color interaction between the two quarks. Using the experimental masses of hadrons, the quark pair parameters are determined between the light quark pairs and the light-heavy quark pairs. Then the parameters of heavy quark pairs ($cc$, $cb$, $bb$) are estimated based on simple quark model assumption. We calculate all masses of doubly and triply heavy-quark baryons. The newly discovered doubly charmed baryon $Ξ_{cc}$ fits into the model with an error of 12 MeV.

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arXiv2017

Decuplet to octet baryon transitions in chiral perturbation theory

We have systematically investigated the decuplet (T) to octet (B) baryon ($T\rightarrow Bγ$) transition magnetic moments to the next-to-next-to-leading order and electric quadruple moments to the next-to-leading order in the framework of the heavy baryon chiral perturbation theory. Our calculation includes the contributions from both the intermediate decuplet and octet baryon states in the loops. Our results show reasonably good convergence of the chiral expansion and agreement with the experimental data. The analytical expressions may be useful to the chiral extrapolation of the lattice simulations of the decuplet electromagnetic properties.

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arXiv2015

Strong decay patterns of the hidden-charm tetraquarks

With the spin rearrangement, we have performed a comprehensive investigation of the decay patterns of the S-wave tetraquarks and P-wave tetraquarks where the P-wave excitation exists either between the diquark and anti-diquark pair or inside the diquark. Especially, we compare the decay patterns of $Y(4260)$ with different inner structures such as the conventional charmonium, the molecule, the P-wave tetraquark and the hybrid charmonium. We notice the $J/ψππ$ mode is suppressed in the heavy quark symmetry limit if $Y(4260)$ is a molecular state. Moreover the hybrid charmonium and hidden-charm tetraquark have very similar decay patterns. Both of them decay into the $J/ψππ$ and open charm modes easily. We also discuss the decay patterns of $X(3872)$, $Y(4360)$, and several charged states such as $Z_c(4020)$. The $h_cπ^{\pm}$ decay mode disfavors the tetraquark assumption of $Z_c(4020)$.

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arXiv2015

Meson Electro-Magnetic Form Factors in an Extended Nambu--Jona-Lasinio model including Heavy Quark Flavors

Based on an extended NJL model including heavy quark flavors, we calculate the form factors of pseudo-scalar and vector mesons. After take into account of the vector-meson-dominance effect which introduce a form factor correction to the quark vector coupling vertices, the form factors and electric radii of $π^+$ and $K^+$ of pseudo-scalar meson in light flavor sector fit the experimental data well. Also the magnetic moments of light vector meson $ρ^+$ and $K^{*+}$ are comparable with other theoretical calculation. The form factors in light-heavy flavor sector are presented to confront with future experiments or theoretical calculations.

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arXiv2014

Hidden-Charm Tetraquarks and Charged Zc States

Experimentally several charged axial-vector hidden-charm states were reported. Within the framework of the color-magnetic interaction, we have systematically considered the mass spectrum of the hidden-charm and hidden-bottom tetraquark states. It is impossible to accommodate all the three charged states $Z_c(3900)$, $Z_c(4025)$ and $Z_c(4200)$ within the axial vector tetraquark spectrum simultaneously. Not all these three states are tetraquark candidates. Moreover, the eigenvector of the chromomagnetic interaction contains valuable information of the decay pattern of the tetraquark states. The dominant decay mode of the lowest axial vector tetraquark state is $J/ψπ$ while its $D^*\bar{D}$ and $\bar{D}^*D^*$ modes are strongly suppressed, which is in contrast with the fact that the dominant decay mode of $Z_c(3900)$ and $Z_c(4025)$ is $\bar{D}D^*$ and $\bar{D}^*D^*$ respectively. We emphasize that all the available experimental information indicates that $Z_c(4200)$ is a very promising candidate of the lowest axial vector hidden-charm tetraquark state.

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arXiv2014

Probing the $XYZ$ states through radiative decays

In this work, we have adopted the spin rearrangement scheme in the heavy quark limit and extensively investigated three classes of the radiative decays: $\mathfrak{M}\to (b\bar{b})+γ$, $(b\bar{b})\to \mathfrak{M}+γ$, $ \mathfrak{M} \to \mathfrak{M}^\prime+γ$, corresponding to the electromagnetic transitions between one molecular state and bottomonium, one bottomonium and molecular state, and two molecular states respectively. We also extend the same formalism to study the radiative decays of the molecular states with hidden charm. We have derived some model independent ratios when the initial or final states belong to the same spin flavor multiplet. Future experimental measurement of these ratios will test the molecular picture and explore the underlying structures of the $XYZ$ states.

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arXiv2013

XYZ States

In the past decade, many new charmonium (or charmonium-like) and bottomonium (or bottomonium-like) states were observed experimentally. I will review these XYZ states which do not fit into the quark model spectrum easily.

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arXiv2012

The heavy mesons in Nambu--Jona-Lasinio model

We propose an extended Nambu--Jona-Lasinio model to include the heavy mesons with the heavy quark symmetry. The quark current-current interaction is generalized to include the heavy quark currents. In order to comply with the heavy quark spin symmetry at the heavy quark limit, the quark mass dependence of the interaction strength is introduced. The light and heavy pseudo-scalar and vector meson, their masses and the weak decay constants, are calculated in the unified frame.

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