arXiv subjects

Kai-Lei Wang

Publications and source records attributed to Kai-Lei Wang.

At least 19 recordsLinked to original sources

arXiv2026

$Ω_c$ baryon spectrum and strong decays in a constituent quark model

In this work, we study the $Ω_c$ baryon spectrum up to the $2P$ excitations within a semi-relativistic constituent quark potential model, where the mixing between different configurations with the same spin-parity numbers is dynamically considered. Furthermore, the strong decay properties for the excited $Ω_c$ states are evaluated within an improved chiral quark model by including the relativistic correction term. In a unified framework, we provide a reasonable explanation of the widths, masses, and mass splittings, for the newly observed $Ω_c$ resonances $Ω_c(3000)$, $Ω_c(3050)$, $Ω_c(3065)$, $Ω_c(3090)$, $Ω_c(3120)$, $Ω_c(3185)$, and $Ω_c(3327)$. It is found that the configuration mixing is crucial for understanding the strong decay properties and mass splittings, while the relativistic correction term of the strong transition operator plays an important role in the states dominated by the radial excitations. We expect our study can provide useful references for establishing a more abundant $Ω_c$ spectrum.

hep-ph↗

arXiv2026

Impact of $N^$ and $Λ^$ resonances on $CP$ violation in $Λ_b^0$ decays

The four-body decay $Λ_b^0\to pK^-π^+π^-$ has led to the first observation of baryonic $CP$ violation. However, the underlying subprocesses $Λ_b^0\to N^* M$ and $Λ_b^0\to Λ^* M$, as well as the roles of excited nucleon ($N^*$) and hyperon ($Λ^*$) resonances, remain largely unexplored. Within the constituent quark model, we identify the relevant resonant states contributing to these underlying two-body transitions, including $N(1535)$, $N(1520)$, $Λ(1670)$, $Λ(1690)$, together with the remaining $1P$-wave baryon states. We obtain the resonant branching fraction ${\cal B}(Λ_b^0\to pK^-π^+π^-) =(30.0^{+2.8+4.0}_{-1.3-3.4}\pm1.8)\times10^{-6}$, while the resulting ${\cal A}_{CP}(Λ_b^0\to pK^-π^+π^-)=(3.18\pm0.11\pm0.13\pm0.11)\%$ provides a natural interpretation of the first observed baryonic $CP$ asymmetry. Our analysis establishes the first comprehensive framework for quantifying the impact of excited baryon resonances in multi-body beauty-baryon decays, with the associated mechanism generally applicable to baryonic $CP$ asymmetries.

hep-ph↗

arXiv2026

Investigating $Ω_c$ spectroscopy in two-body $Ω_b$ decays

We investigate the $1S$-, $1P$-, $2S$-, and $1D$-wave $Ω_c(css)$ spectroscopy through the non-leptonic decays of $Ω_b^-$ baryon within the constituent quark model. For the lowest-lying $1S$-wave $Ω_c$ state, we obtain the branching fractions ${\cal B}(Ω_b^- \to Ω_c^0 π^-,Ω_c^0 ρ^-)=(1.2,6.3) \times 10^{-3}$, which are consistent with existing model predictions. For $Ω_c(3000)$, $Ω_c(3050)$, $Ω_c(3065)$, and $Ω_c(3090)$, observed in the proton-proton and $e^+ e^-$ collisions and interpreted as members of the $1P$-wave multiplet (collectively denoted as $Ω_c^{**}$), we predict the branching fractions of $Ω_b^-\toΩ_c^{**}π^-,Ω_c^{**}ρ^-$ at the level of $10^{-3}$. Assigning the newly observed $Ω_c(3327)$ baryon to a $1D$-wave excitation with $J^P=5/2^+$ or $7/2^+$, we obtain ${\cal B}[Ω_b^-\to Ω_c(3327)^0π^-,Ω_c(3327)^0ρ^-] =(2.0,5.7)\times 10^{-3}$ or $(4.6,0.8)\times 10^{-3}$, respectively. The pronounced differences between these two scenarios provide a clear discriminant that can be tested in future measurements at LHCb.

hep-ph↗

arXiv2025

Production of excited $Λ_c^+$ baryons through $Λ_b$ hadronic weak decays

In this work, to establish a more abundant $Λ_c$ baryon spectrum, we discuss the production potentials of the excited $Λ_c$ baryons through $Λ_b$ hadronic weak decays within a constituent quark model. Based on our successful explanations of the existing experimental data for the $Λ_b \to Λ_c(π^-, K^{-}, D^{-}, D^{-}_s, D_s^{*-})$ processes, we further calculate the decay rates of the $Λ_b$ baryon into the $1P$-, $1D$-, $2S$-, $3S$-, $2P$-, $1F$-, and $2D$-wave $Λ_c$ excited states. It is found that these $Λ_c$ excitations have a large production rate in the $Λ_b$ hadronic weak decay process associated $π^-$ meson emitting, i.e., $Λ_b\to Λ_c^{*}π^-$, their branching fractions can reach up to $\mathcal{O}(10^{-3})$. To search for the higher $3S$-, $2P$-, $1F$-, and $2D$-wave $Λ_c$ states, the $Λ_b \to Λ_c (3S) π^-\to D^{*0}p π^-$, and $Λ_b\to Λ_c(2P,2D,1F) π^-\to D^{(*)0}pπ^-$ decays are worth observing in future experiments.

hep-ph↗

arXiv2025

Excited $Ω$ hyperon in charmful $Ω_b$ weak decays

We investigate the sextet $b$-baryon decay processes $Ω_b\to J/ψΩ^{(*)}$,where $Ω^*$ represents the $1P$-, $1D$- and $2S$-wave excited $Ω$ hyperons in the spectroscopy. Using the constituent quark model, we obtain ${\cal B}(Ω_b \to J/ψΩ)=8.8\times 10^{-4}$, which agrees with the previous studies to the order of magnitude. By identifying $Ω(2012)$ as $Ω(1^2P_{3/2^-})$, ${\cal B}(Ω_b \to J/ψΩ(2012))=1.1\times 10^{-3}$ can be similarly significant. Additionally, $Ω(1^2D_{5/2^+})$ and $Ω(1^4D_{3/2^+},1^4D_{5/2^+})$ states exhibit production rates of 0.5, and (0.6, 0.8), respectively, relative to their ground-state counterpart. Notably, our findings suggest that ${\cal B}(Ω_b\to J/ψΩ(2^2S_{1/2^+},2^4S_{3/2^+}))$ are as large as $(4.5,20)\times 10^{-4}$, making them accessible to experiments at LHCb.

hep-ph↗

arXiv2025

Charmful two-body $Ω_b$ decays in the light-front quark model

We investigate the singly and doubly charmful two-body $Ω_b^-$ decays using the light-front quark model. Our findings reveal that most branching fractions calculated in this study, such as ${\cal B}(Ω_b^-\toΞ^- D^0,Ξ^{-}D^{*0})$, can be ten to one hundred times larger than those reported in previous calculations. Additionally, we interpret the ratio ${\cal B}(Ω_b^-\toΩ^- J/ψ)/{\cal B}(Ω_b^-\toΩ^- η_c)\simeq 3.4$ within the helicity framework. While the decay involving external $W$-boson emission appears to be suppressed by the $b\to u \bar c s$ weak transition, it still yields a significant branching fraction. For instance, ${\cal B}(Ω_b^-\toΞ^0 D_s^{*-})=(5.9-14.2)\times 10^{-5}$, ${\cal B}(Ω_b^-\toΞ^{*0}D_s^{-})=(6.7-12.1)\times10^{-5}$, and ${\cal B}(Ω_b^-\toΞ^{*0}D_s^{*-})=(12.8-26.7)\times10^{-5}$, with values reaching as large as $10^{-4}$. These predictions are well within the experimental reach of LHCb.

hep-ph↗

arXiv2024

Toward discovering the excited $Ω$ baryons through nonleptonic weak decays of $Ω_c$

The nonleptonic weak decay processes $Ω_c \to Ωπ^+/Ω(1P)π^+/Ω(1D)π^+/Ω(2S)π^+$ are studied using the constituent quark model. The branching fraction of $Ω_c \to Ωπ^+$ is predicted to be $1.0\%$. Considering the newly observed $Ω(2012)$ resonance as a conventional $1P$-wave $Ω$ excite state with spin-parity $J^P=3/2^-$, the newly measured ratio $\mathcal{B}[Ω_c\to Ω(2012)π^+ \to (Ξ\bar{K})^-π^+ ]/\mathcal{B}[Ω_c\to Ωπ^+]$ at Belle can be well understood. Besides, the production rates for the missing $1P-$wave state $Ω(1^2P_{1/2^-})$, two spin quartet $1D-$wave states $Ω(1^4D_{1/2^+})$ and $Ω(1^4D_{3/2^+})$, and two $2S$-wave states $Ω(2^2S_{1/2^+})$ and $Ω(2^4S_{3/2^+})$ are also investigated. It is expected that these missing excited $Ω$ baryons should have large potentials to be discovered through the nonleptonic weak decays of $Ω_c$ in forthcoming experiments by Belle II and/or LHCb.

hep-ph↗

arXiv2022

Toward establishing the low-lying $P$-wave excited $Σ_c$ baryon states

In this study, by combining the equal spacing rule with recent observations of $Ω_c(X)$ and $Ξ_c(X)$ baryons, we predict the spectrum of the low-lying $λ$-mode $1P$-wave excited $Σ_c$ states. Furthermore, their strong decay properties are predicted using the chiral quark model and the nature of $Σ_c(2800)$ is investigated by analyzing the $Λ_cπ$ invariant mass spectrum. The $Σ_c(2800)$ structure observed in the $Λ_c π$ mass spectrum was found to potentially arise from two overlapping $P$-wave $Σ_c$ resonances, $Σ_c(2813)3/2^-$ and $Σ_c(2840)5/2^-$. These resonances have similar decay widths of $Γ\sim 40$ MeV and predominantly decay into the $Λ_c π$ channel. The $Σ_c(2755)1/2^-$ state is likely to be a very narrow state with a width of $Γ\sim 15$ MeV, with its decays almost saturated by the $Λ_c π$ channel. Additionally, evidence of the $Σ_c(2755)\frac{1}{2}^-$ resonance as a very narrow peak may be seen in the $Λ_cπ$ invariant mass spectrum. The other two $P$-wave states, $Σ_c(2746)\frac{1}{2}^-$ and $Σ_c(2796)\frac{3}{2}^-$, are relatively narrow states with similar widths of $Γ\sim 30$ MeV and predominantly decay into $Σ_cπ$ and $Σ^{*}_cπ$, respectively. We hope our study can provide useful references for discovering these low-lying $P$-wave states in forthcoming experiments.

hep-ph↗

arXiv2022

Correlation between nuclear temperatures and symmetry energy in sub-saturation

A study of the correlation between nuclear temperatures and symmetry energy is presented for heavy-ion collisions at intermediate energies via the isospin-dependent quantum molecular-dynamics model. It is found that different symmetry energy parameters will change the density and kinetic energy distribution of the hot nuclei. More importantly, nuclear temperatures that are based on kinetic energy properties can be used to study symmetry energy information.

nucl-th↗

arXiv2020

Understanding the newly observed $Ξ_c^0$ states through their decays

Inspired by the newly observed $Ξ_c^0$ states by the LHCb Collaboration, we investigate the OZI-allowed two-body strong decays of the $λ$-mode $1P$ wave $Ξ'_c$ states within the chiral quark model. Our results indicate that: (i) the newly observed states $Ξ_c(2923)^0$ and $Ξ_c(2939)^0$ are good candidates of the $λ$-mode $1P$ wave $Ξ'_c$ states with the spin-parity $J^P=3/2^-$, namely $|^4P_λ3/2^-\rangle$ and $|^2P_λ3/2^-\rangle$, respectively. (ii) The another newly observed state $Ξ_c(2965)^0$ mostly corresponds to the $λ$-mode $1P$-wave $Ξ'_c$ state with the spin-parity $J^P=5/2^-$, namely $|^4P_λ5/2^-\rangle$. (iii) For the two $λ$-mode $J^P=1/2^-$ mixed states, the $|P_λ~1/2^-\rangle_1$ is a narrow state with a width of $Γ\sim15$ MeV and mainly decays into $Ξ'_cπ$; while the $|P_λ~1/2^-\rangle_2$ state has a width of $Γ\sim52$ MeV and dominantly decays into $Ξ_cπ$ and $Λ_cK$ channels. If the broad structure around $2880$ MeV observed at LHCb arises from the new $Ξ^0_c$ state, this state is very likely to be the $|P_λ~1/2^-\rangle_2$ state.

hep-ph↗

arXiv2020

Possible interpretation of the newly observed $Ω_b$ states

Inspired by the newly observed $Ω_b$ states by the LHCb Collaboration, we investigate the two-body strong decays of the low-lying $λ$-mode $Ω_b$ baryons up to $N=2$ shell using the chiral quark model within the $j$-$j$ coupling scheme. Our results indicate that: (i) the newly observed states $Ω_b(6316)^-$ and $Ω_b(6330)^-$ are good candidates of the light spin $j=1$ states, while the spin-parity $J^P=1/2^-$ and $J^P=3/2^-$ cannot be distinguished. The other two states, $Ω_b(6340)$ and $Ω_b(6350)$ mostly correspond to the light spin $j=2$ states, while the spin-parity $J^P=3/2^-$ and $J^P=5/2^-$ cannot be distinguished as well.(ii) The $2S$ states with spin-parity $J^P=1/2^+$ and $J^P=3/2^+$, respectively, might be narrow states with a width of $Γ<2$ MeV. (iii) The $1D$ states are not broad and the total decay widths vary from several to dozens of MeV, which have a good potential to be observed in future experiments.

hep-ph↗

arXiv2020

The $ss \bar s \bar s$ tetraquark states and the newly observed structure $X(2239)$ by BESIII Collaboration

We investigate the mass spectrum of the $ss \bar s \bar s$ tetraquark states within the relativized quark model. By solving the Schrödinger-like equation with the relativized potential, the masses of the $S-$ and $P-$wave $ss \bar s \bar s$ tetraquarks are obtained. The screening effects are also taken into account. It is found that the observed resonant structure $X(2239)$ in the $e^+e^- \to K^+K^-$ process by BESIII Collaboration can be assigned as a $P-$wave $1^{--}$ $ss \bar s \bar s$ tetraquark state. Furthermore, the radiative transition and strong decay behaviors of this structure are also estimated, which can provide helpful information for future experimental searches.

hep-ph↗

arXiv2019

$Ω$ baryon spectrum and their decays in a constituent quark model

Combining the recent developments of the observations of $Ω$ sates we calculate the $Ω$ spectrum up to the $N=2$ shell within a nonrelativistic constituent quark potential model. Furthermore, the strong and radiative decay properties for the $Ω$ resonances within the $N=2$ shell are evaluated by using the masses and wave functions obtained from the potential model. It is found that the newly observed $Ω(2012)$ resonance is most likely to be the spin-parity $J^P=3/2^-$ $1P$-wave state $Ω(1^{2}P_{3/2^{-}})$, it also has a large potential to be observed in the $Ω(1672)γ$ channel. Our calculation shows that the 1$P$-, 1$D$-, and 2$S$-wave $Ω$ baryons have a relatively narrow decay width of less than 50 MeV. Based on the obtained decay properties and mass spectrum, we further suggest optimum channels and mass regions to find the missing $Ω$ resonances via the strong and/or radiative decay processes.

hep-ph↗

arXiv2019

Interpretation of the newly observed $Λ_b(6146)^{0}$ and $Λ_b(6152)^0$ states in a chiral quark model

The strong decays of the low-lying $λ$-mode $Λ_b(1D,2S)$ and $Σ_b(2S)$ states are studied in a chiral quark model. We find that: (i) the newly observed $Λ_b(6146/6152)$ resonances in the $Λ_bπ^+π^-$ spectrum by the LHCb Collaboration might be explained with the $λ$-mode $Λ_b(1D)$ states in the quark model. It should be emphasized that whether the structure in the $Λ_bπ^+π^-$ spectrum correspond to two states or one state should be further clarified with more observations in future experiments. (ii) The $Λ_b(2S)$ $|J^P = \frac{1}{2}^+,0\rangle$ state mainly decays into $Σ_b^*π$ channel, which may be an ideal channel for searching for this $Λ_b(2S)$ state in future experiments. (iii) The $Σ_b(2S)$ $|J^P = \frac{1}{2}^+,1 \rangle$ and $|J^P = \frac{3}{2}^+,1 \rangle$ dominantly decay into $Λ_bπ$ with $Γ\simeq 3.82$ MeV and $Γ\simeq 4.72$ MeV, respectively.

hep-ph↗

arXiv2018

Interpretation of the newly observed $Σ_b(6097)^{\pm}$ and $Ξ_b(6227)^-$ states as the $P$-wave bottom baryons

The strong decays of the $P$-wave $Σ_b$, $Ξ_b'$ and $Ω_b$ baryons are investigated with a constituent quark model in the $j$-$j$ coupling scheme. The results show that the newly observed $Σ_b(6097)$ and $Ξ_b(6227)$ states by the LHCb collaboration can be assigned as the $λ$-mode $P$-wave singly bottom baryons. Given the heavy quark symmetry, both the $Σ_b(6097)$ and $Ξ_b(6227)$ states favor the light spin $j=2$ states with spin-parity numbers $J^P=3/2^-$ or $J^P=5/2^-$. More $P$-wave singly bottom baryons are most likely to be observed in future experiments for their relatively narrow width.

hep-ph↗

arXiv2018

Strong and radiative decays of the low-lying $D$-wave singly heavy baryons

The strong and radiative decays of the low-lying $λ$-mode $D$-wave $Λ_{c(b)}$, $Σ_{c(b)}$, $Ξ_{c(b)}$, $Ξ_{c(b)}'$, and $Ω_{c(b)}$ baryons are studied in a constituent quark model. Our calculation shows the following: (i) The missing $λ$-mode $D$-wave $Ω_{c(b)}$, $Λ_{b}$, and $Ξ_{b}$ baryons have a relatively narrow decay width of a few MeV or a few tens of MeV and their dominant strong and radiative decay channels can be ideal for searching for their signals in future experiments. (ii) The $λ$-mode $1D$-wave excitations in the $Σ_{c(b)}$ and $Ξ_{c(b)}'$ families appear to have a relatively broad width of $\sim 50-200$ MeV.Most of the $1D$-wave states have large decay rates into the $1P$-wave heavy baryons via the pionic or kaonic strong decay processes, which should be taken seriously in future observations. (iii) Both $Λ_c(2860)$ and $Ξ_c(3050)$ seem to favor the $J^P=3/2^+$ excitation $|^2D_{λλ} \frac{3}{2}^+ \rangle$ of $\bar{\mathbf{3}}_F$, while both $Λ_c(2880)$ and $Ξ_c(3080)$ may be assigned as the $J^P=5/2^+$ excitation $|^2D_{λλ} \frac{5}{2}^+ \rangle$ of $\bar{\mathbf{3}}_F$. The nature of $Ξ_c(3050)$ and $Ξ_c(3080)$ could be tested by the radiative transitions $Ξ_c(3055)^0\to Ξ_c(2790)^0 γ$ and $Ξ_c(3080)^0 \to Ξ_c(2815)^0 γ$, respectively.

hep-ph↗

arXiv2018

Strong and radiative decays of the low-lying $S$- and $P$-wave singly heavy baryons

The strong and radiative decays of the low-lying $S$- and $P$-wave $Λ_{c(b)}$, $Σ_{c(b)}$, $Ξ_{c(b)}$, $Ξ_{c(b)}'$ and $Ω_{c(b)}$ baryons are systematically studied in a constituent quark model. We find that the radiative decay mode $Λ_b^0γ$ could be very useful for us to establish the missing neutral states $Σ_b^{0}$ and $Σ_b^{*0}$. Our calculation shows that most of those missing $λ$-mode $P$-wave singly heavy baryons have relatively narrow decay width of less than 30 MeV. Their dominant strong and radiative decay channels can be ideal for searching for their signals in future experiment. Configuration mixings between the $J^P=1/2^-$ states $|^2P_λ \frac{1}{2}^- \rangle$ and $|^4P_λ \frac{1}{2}^- \rangle$ of the $\mathbf{6}_F$ multiplet are discussed. The $Ξ_c(2930)^0$ state seems to favor the mixed state $|Ξ_c'~ P_λ\frac{1}{2}^-\rangle_2$ with $J^P=1/2^-$. The $Σ_c(2800)$ resonance may be assigned to $|Σ_c~ ^2P_λ \frac{3}{2}^- \rangle$ with $J^P=3/2^-$ or $|Σ_c~ ^4P_λ \frac{5}{2}^- \rangle$ with $J^P=5/2^-$. In general, the excitations of $|^2P_λ \frac{3}{2}^- \rangle$ and $|^4P_λ \frac{5}{2}^- \rangle$ of the $\mathbf{6}_F$ multiplet have similar strong decay properties. In order to to identify them, angular distributions of their decays in either strong decay modes or radiative transitions should be needed.

hep-ph↗

arXiv2017

Mass spectra and radiative transitions of doubly heavy baryons in a relativized quark model

We study the mass spectra and radiative decays of doubly heavy baryons within the diquark picture in a relativized quark model. The mass of the $J^P=1/2^+$ $Ξ_{cc}$ ground state is predicted to be 3606 MeV, which is consistent with the mass of $Ξ_{cc}^{++}(3621)$ newly observed by the LHCb collaboration. The predicted mass gap between two $S$ wave states, $Ξ_{cc}^*$ ($J^P=3/2^+$) and $Ξ_{cc}$ ($J^P=1/2^+$), is 69 MeV. Furthermore, the radiative transitions of doubly heavy baryons are also estimated by using the realistic wave functions obtained from relativized quark model. The radiative decay widths of $Ξ_{cc}^{*++} \to Ξ_{cc}^{++}γ$ and $Ξ_{cc}^{*+} \to Ξ_{cc}^+γ$ are predicted to be about 7 and 4 keV, respectively. These predictions of doubly heavy baryons can provide helpful information for future experimental searches.

hep-ph↗