arXiv subjects

Xin-Zhen Weng

Publications and source records attributed to Xin-Zhen Weng.

12 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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arXiv2024

Systematics of fully heavy dibaryons

We systematically study the mass spectra of the fully heavy dibaryons in an extended chromomagnetic model, which includes both the colorelectric and chromomagnetic interactions. We find no stable state below the corresponding baryon-baryon thresholds. Besides the masses, we also estimate the relative width ratios of the two-body decay channels. We hope our study will be of help for future experiments.

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arXiv2024

Properties of $Q^{5}q$ dibaryons

We investigate heavy flavor dibaryons with five heavy quarks $Q$ ($Q=\{c,b\}$) and one light quark $q$ ($q=\{u,d,s\}$), namely the $Q^{5}q$ dibaryons. In the framework of an extended chromomagnetic model, we systematically study the mass spectrum of these dibaryons. We find no stable state below the corresponding baryon-baryon thresholds. In addition to the analysis of the masses, we also study their two body decay properties by estimating the relative width ratios of the decay channels. We hope our study will be of help for future experiments.

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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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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

A possible explanation of the threshold enhancement in the process $e^+e^-\rightarrow Λ\barΛ$

Inspired by the recent measurement of the process $e^+e^-\rightarrow Λ\barΛ$, we calculate the mass spectrum of the $ϕ$ meson with the GI model. For the excited vector strangeonium states $ϕ(3S,~4S,~5S,~6S)$ and $ϕ(2D,~3D,~4D,~5D)$, we further investigate the electronic decay width with the Van Royen-Weisskopf formula, and the partial widths of the $Λ\barΛ$, $Ξ^{-(*)}\barΞ^+$, and $Σ^{+(*)}\barΣ^{-(*)}$ decay modes with the extended quark pair creation model. We find that the electronic decay width of the $D$-wave vector strangeonium is about $3\sim8$ times larger than that of the $S$-wave vector strangeonium. Around 2232 MeV the partial decay width of the $Λ\barΛ$ mode can reach up to several MeV for $ϕ(3^3S_1)$, while the partial $Λ\barΛ$ decay width of $ϕ(2^3D_1)$ is $\mathcal{O}(10^{-3})$ keV. If the threshold enhancement reported by the BESIII Collaboration arises from the strangeonium meson, this state is very likely to be the $ϕ(3^3S_1)$ state. We also note that the $Λ\barΛ$ and $Σ^{+}\barΣ^{-}$ partial decay widths of the states $ϕ(3^3D_1)$ and $ϕ(4^3S_1)$ are about several MeV, respectively, which are enough to be observed in future experiments.

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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

A new decay mode of higher charmonium

We calculate the $Λ_c\barΛ_c$ partial decay width of the excited vector charmonium states around 4.6 GeV with the quark pair creation model. We find that the partial decay width of the $Λ_c\barΛ_c$ mode can reach up to several MeV for $ψ(4S,~5S,~6S)$. In contrast, the partial $Λ_c\barΛ_c$ decay width of the states $ψ(3D,~4D,~5D)$ is less than one MeV. If the enhancement $Y(4630)$ reported by the Belle Collaboration in $Λ_c\barΛ_c$ invariant-mass distribution is the same structure as $Y(4660)$, the $Y(4660)$ resonance is most likely to be a $S$-wave charmonium state.

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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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