arXiv subjects

Qi-Fang Lü

Publications and source records attributed to Qi-Fang Lü.

At least 19 recordsLinked to original sources

arXiv2026

Exploring interference between $P_{c \bar c}$ resonances and background in the pion-induced reaction

We present a phenomenological study of the near-threshold $π^- p \to J/ψn$ reaction, focusing on the interference effects between the $s-$channel $P_{c \bar c}$ resonances and non-resonance background. This reaction provides a complementary probe to photoproduction for investigating the nature of the hidden-charm pentaquark states. Using an effective Lagrangian approach, we construct scattering amplitudes for $J^P=1/2^-$ and $3/2^-$ $P_{c\bar c}$ states under two spin-parity scenarios, with the background dominated by the $t-$channel $ρ$ meson exchange. We find that the interference can produce peaks, dips, or complex line shapes depending on the relative phase, in contrast to the simple resonance peaks commonly reported in previous theoretical studies. The two spin-parity scenarios yield qualitatively similar patterns, indicating that our main conclusion is robust. Given the current scarcity of experimental data for the pion-induced channel, we emphasize the urgent need for future measurements at J-PARC to understand the dynamics of the $J/ψN$ interaction near threshold and to search for the heavy pentaquark states.

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arXiv2026

Theoretical description of the $D^{+} \to \bar{K}^{0} π^{+} π^{0} π^{0}$ reaction

We study the $D^{+} \rightarrow \bar{K}^{0} π^{+} π^{0} π^{0}$ reaction, which shows two clear structures: the $\bar{K}^{*0}$ and $ρ^{+}$ in the $\bar{K}^{0} π^{0}$ and $π^{+} π^{0}$ mass distributions, respectively. The study is done starting from the quark level with external and internal emission and hadronizing a pair of quarks to produce a vector and two pseudoscalars. We also consider another mechanism, which does not require hadronization of quark pairs: the direct production of $\bar{K}^{*0}$ and $ρ^{+}$. With the help of six unknown parameters which are fitted to the data, we are able to get a very good agreement with experimental data for the $\bar{K}^{0} π^{0}$ and $π^{+} π^{0}$ mass distributions and a qualitative one for the rest of mass distributions which do not show any particular structure experimentally.

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arXiv2025

An analysis on doubly bottom molecular tetraquarks composed of $H_{(s)}$ and $T_{(s)}$ doublets

In this work, we investigate the doubly bottom $H_{(s)}\bar{T}_{(s)}$ and $H_{(s)}T_{(s)}$ systems by adopting the one-boson-exchange model, where $H_{(s)}$ and $T_{(s)}$ represent $S$-wave $B^{(*)}_{(s)}$ and $P$-wave $B^{(*)}_{(s)1,2}$ doublets, respectively. For the $H\bar{T}$ systems, we predict some loosely bound states in the $I(J^{PC})=0(1^{-\pm})$ $B\bar{B}_{1}$, $I(J^{PC})=0(2^{-\pm})$ $B\bar{B}_{2}^{*}$, $I(J^{PC})=0(1^{-\pm})$ $B^*\bar{B}_{1}$ and $I(J^{PC})=0(2^{-\pm})$ $B^*\bar{B}_{2}^{*}$ channels, which are the most promising hidden bottom molecular tetraquarks. For the $HT$ systems, the $B^*B_1$ channels with quantum numbers $I(J^P) = 0(1^{-}), 0(2^{-})$ and the $B^*B_2^*$ channels with $I(J^P) = 0(2^{-})$ are also likely candidates for forming molecular tetraquarks. In contrast, no molecular candidates have been identified in the bottom-strange sectors. One can hope that our predictions will provide valuable insights to the LHCb and Belle II Collaborations as they continue to explore this fascinating field through experimental research.

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arXiv2025

A coupled-channel perspective analysis on bottom-strange molecular pentaquarks

At present work, we systematically study various bottom-strange molecular pentaquarks to search for possible bound states and resonances by adopting one-boson-exchange model within complex scaling method. According to our calculations, we predict several bound and resonant states for bottom baryon $Y_{b}(Λ_b,Σ_b) \bar K^{(*)}$ and $Y_{b} K^{(*)}$ systems. In particular, a bound state in the $I(J^P)=1/2(1/2^-)$ $Σ_{b}\bar{K}/Λ_{b}\bar{K}^*/Σ_{b}\bar{K}^*$ system may correspond to the particle $Ξ_{b}(6227)$. Meanwhile, the predicted bound state with $6303\sim6269~\rm{MeV}$ in the $I(J^P)=1/2(1/2^-)Σ_bK/Λ_bK^*/Σ_bK^*$ system is flavor exotic and does not appear in the spectroscopy of conventional baryons, which provides a practical way to clarify the nature of particle $Ξ_b(6227)$. We highly hope that our proposals can offer helpful information for the future experimental searches.

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arXiv2025

Understanding the low-lying $Ω_c$ structures from a coupled-channel perspective

We perform a systematic analysis of the low-lying $Ω_c$ structures in a coupled-channel approach. The couplings between meson-baryon channels, $Ξ_c \bar K$, $Ξ_c^{\prime} \bar K$, $Ξ_c^{*} \bar K$, $Ω_cη$ and $Ω_c^{*}η$, and three-quark bare states $Ω_c(1P_λ)$ are considered. We predict a bound state $Ω_c(2954)$ below the $Ξ_c \bar K$ threshold with $(J^P,j)=(1/2^-,0)$, which can be studied in the final states of $Ω_c^{(*)} π$ and $Ω_c^{(*)} γ$. Also, the resonances $Ω_c(3000)$ and $Ω_c(3050)$ can be classified as the lower $(J^P,j)=(1/2^-,1)$ and $(J^P,j)=(3/2^-,1)$ states, respectively. Our present assignments based on this coupled-channel perspective are significantly different from those of traditional three-quark picture and of molecular scenario. The future BelleII and LHCb experiments can search for the bound state $Ω_c(2954)$ and measure the spin-parities of particles $Ω_c(3000)$ and $Ω_c(3050)$ to test our predictions.

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arXiv2025

Exploring bottom-charmed molecular tetraquarks with the complex scaling method

In this work, we adopt the one-boson exchange model to analyze the $D^{(*)}_{(s)}B^{(*)}_{(s)}$ interactions from a coupled-channel perspective. For the $I(J^{P})=1(1^{+})$ $DB^{*}/D^*B/D^*B^{*}$ system, employing the complex scaling method, we obtain a loosely bound state and two resonant states located below the $DB^{*}$, $D^*B$, and $D^*B^{*}$ thresholds, respectively. Assuming that the charmonium-like states $T_{c\bar{c}1}(3900)$ and $T_{c\bar{c}1}(4020)$, as well as the bottomonium-like states $T_{b\bar{b}1}(10610)$ and $T_{b\bar{b}1}(10650)$, are molecular states near their respective thresholds, we suggest that the predicted states in the $I(J^P)=1(1^+)$ $D^{(*)}_{(s)}B^{(*)}_{(s)}$ system could be their bottom-charmed analogues. In addition, we extend our analysis to other $D^{(*)}_{(s)}B^{(*)}_{(s)}$ combinations with various quantum numbers. Our results suggest that some exotic structures may exist in the bottom-charmed sector. Finally, we collect the possible decay channels for future experimental observations. The $B_c/B_c^*$ plus a light meson are the ideal final state to search for the bound states, while the $D_{(s)}^{(*)}B_{(s)}^{(*)}$ channels are suitable for the resonances. We highly recommend that the future experiments hunt for these bottom-charmed exotic particles.

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arXiv2025

Strong decays of $P-$wave doubly charmed and bottom baryons

In this work, we investigate the strong decays for $P-$wave excited states of doubly charmed and bottom baryons in the constituent quark model. Our results indicate that some $λ-$mode $Ξ_{cc/bb}(1P)$ and $Ω_{cc/bb}(1P)$ states are relatively narrow, which are very likely to be discovered by future experiments. The light meson emissions for the low-lying $ρ-$mode states are highly suppressed due to the orthogonality of wave functions between initial and final states. Moreover, the strong decay behaviors for doubly charmed and bottom baryons preserve the heavy superflavor symmetry well, where the small violation originates from the finite heavy quark masses and different phase spaces. We hope that present theoretical results for undiscovered doubly charmed and bottom baryons can provide helpful information for future experiments and help us to better understand the heavy quark symmetry.

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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.

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arXiv2024

Reveal short range interactions between $u/d$ quarks in the $NN$, $D_{03}$, and $D_{30}$ systems

The dynamic mechanism of short range interactions between $u/d$ quarks remains an open and challenging problem. In order to reveal this quark dynamics, we perform a systematic analysis of $NN$, $D_{03}$, and $D_{30}$ systems in the (extended) chiral SU(3) constituent quark models. By comparing results calculated with different models and different parameter sets, the effects of one gluon exchange and vector meson exchange terms are carefully examined. The results indicate that the vector meson exchange interactions dominate the short range interactions between $u/d$ quarks, whereas the small residual one gluon exchange coupling strength is also allowed.

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arXiv2024

Predicting hidden bottom molecular tetraquarks with a complex scaling method

In present work, we perform a coupled-channel analysis of $B^{(*)}_{(s)}\bar{B}^{(*)}_{(s)}$ systems with the one-boson-exchange potentials. We first study the $I(J^{PC})=1(1^{+-})$ $B\bar{B}^{*}/B^{*}\bar{B}^{*}$ system to describe the $Z_{b}(10610)$ and $Z_{b}(10650)$ particles as molecular states and determine the reasonable range of cutoff parameter $Λ$. Then, other $B^{(*)}_{(s)}\bar{B}^{(*)}_{(s)}$ combinations with different quantum numbers are systematically investigated. Some bound states and resonances appear in the isoscalar systems, while only several shallow bound states exist for isovector systems. Far away from the excited conventional $P-$wave bottomium, these predicted states can be easily identified as exotic particles both theoretically and experimentally. Moreover, the $η_b(nS)/Υ(nS)$ plus light mesons are the excellent final states to search for the bound states, while the $B\bar B^*+h.c.$ and $B^* \bar B^*$ channels are suitable for the resonances. We highly recommend that the LHCb and Belle II Collaborations can hunt for these bottomonium-like states in future.

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arXiv2024

Canonical interpretation of the newly observed $J^P =1^+$ structure $X(2085)$

Inspired by the newly observed $X(2085)$ by the BESIII Collaboration, we study the strong decay behaviors of excited axialvector strange mesons within the quark pair creation model. Our results indicate that the $K_1(1793)/K_1(1861)$ can be regarded as the same $K_1(2P)$ state, and the $K_1(1911)$ is assigned as the $K_1(2P^\prime)$ state. Considering the mass, spin-parity, and decay behaviors, we interpret the newly observed $X(2085)$ as the radially excited $K_1(3P)$ state, which mainly decays into the $ρ(1450) K$, $ω(1420)K$, $πK^*(1410)$, $ρK_1(1270)$, and $ρK^*(892)$ final states. Also, the width of $K_1(3P^\prime)$ state is predicted to be about 300 MeV, which can be searched for by future experiments. We expect that present calculations can help us to better understand the nature of the $X(2085)$ structure.

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arXiv2024

Bottom-charmed baryons in a nonrelativistic quark model

In this work, we study the low-lying mass spectra for bottom-charmed baryons in a nonrelativistic quark model by solving the three-body Schrödinger equation. The lowest $Ξ_{bc}$, $Ξ_{bc}^\prime$, $Ω_{bc}$, and $Ω_{bc}^\prime$ states are predicted to be about 6979, 6953, 7109, and 7092 MeV, respectively. Also, the strong decays for the low-lying excited states are investigated. Our results indicate that some of $λ-$mode $P-$wave bottom-charmed baryons are relatively narrow, which can be searched for in future experiments. For the low-lying $ρ-$mode and $ρ-λ$ hybrid states, their strong decays are highly suppressed and they can survive as extremely narrow states. Moreover, the mass spectra and strong decays for bottom-charmed baryons preserve the heavy quark symmetry well. We hope our calculations can provide helpful information for further experimental and theoretical researches.

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arXiv2023

Production of dibaryon $d_{NΩ}$ in kaon induced reactions

In this work, we propose to investigate the $d_{NΩ}$ dibaryon production in the process $K^- p \rightarrow d_{NΩ} \barΞ^0$ by utilizing the kaon beam with the typical momentum to be around 10 GeV, which may be available at COMPASS, OKA@U-70 and SPS@CERN. The cross sections for $K^- p \rightarrow d_{NΩ} \barΞ^0$ are estimated and in particular, the magnitude of the cross sections are evaluated to be several hundreds nanobarn at $P_K=20$ GeV. Considering that $d_{NΩ}$ dibaryon dominantly decay into $ΞΛ$ and $ΞΣ$, we also estimate the cross sections for $K^- p \to Ξ^0 Λ\barΞ^0$ and $K^- p \to Ξ^- Σ^+ \barΞ^0$, where the $d_{NΩ}$ dibaryon can be observed in the invariant mass distributions of $Ξ^0 Λ$ and $Ξ^- Σ^+ $, respectively.

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arXiv2023

Light meson emissions of the selected charmonium-like states within compact tetraquark configurations

We adopt the quark pair creation model to investigate the light meson emissions of several charmonium-like states. The quark pair creation model is applied to the four-body systems, and we calculate the pion/kaon emissions of the $X(4700)$, $Z_c(4430)$, $Y(4230)$, $Y(4360)$, $Y(4390)$ and $Y(4660)$ within the compact tetraquark assumptions. It is found that the pion/kaon decay widths for the $X(4700)$ and $Z_c(4430)$ are relatively small, while the partial decay widths for the resonances $Y(4230)$, $Y(4360)$, $Y(4390)$ and $Y(4660)$ are significant. We expect that our exploration of these decay behaviors can provide useful information for future experimental searches and theoretical interpretations.

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arXiv2023

Understanding the nature of $Ω(2012)$ in a coupled-channel approach

We perform a systematic analysis of the mass and strong decays of the $Ω(2012)$ resonance in a coupled-channel approach of a bare three-quark state and a composite meson-baryon state. Besides the coupling of the bare state and $Ξ^* \bar K$ channel, the effective meson-baryon interactions are also included. We find a pole with mass of $2008$ MeV by solving the Bethe-Salpeter equation. The calculated decay widths and its ratios of branching fractions $\mathcal {R}_{Ξ\bar K}^{Ξπ\bar K}$ agree well with the new experimental measurement by Belle Collaboration. Our results suggest that both three-quark core and $Ξ^* \bar K$ channel are essential for the description of the $Ω(2012)$ resonance. We expect that present calculations can help us to better understand the nature of $Ω(2012)$ resonance.

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arXiv2022

Fully-heavy hexaquarks in a constituent quark model

In this work, we systematically investigate the mass spectra of fully-heavy hexaquarks within a constituent quark model by including the color Coulomb potential, linear confining potential, and spin-spin interactions. Our results show that all of the fully-heavy hexaquarks lie above the corresponding baryon-baryon thresholds, and thus no stable compact one exists. These states may subsist as resonances and decay into two fully-heavy baryons easily through the fall-apart mechanism, which can be searched in future experiments.

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arXiv2022

Canonical interpretation of the $D_{s0}(2590)^{+}$ resonance

The $D_{s0}(2590)^{+}$ resonance observed by LHCb Collaboration is a strong candidate of the $D_{s}(2^1S_0)$ state according to its spin parity and strong decay mode. However, the measured mass seems relatively lower than the previous theoretical predictions, which interests the coupled channel interpretations in the literature. In this work, we adopt an alternate approach, taking into account the screening effects in the potential model, to describe the $D_{s0}(2590)^{+}$ resonance. The mass spectrum and strong decays of the excited charmed-strange mesons are investigated within the modified relativized quark model and $^3P_0$ model. The calculated mass and width of the $D_{s0}(2590)^{+}$ are consistent with the experimental observations, which indicate that it can be reasonably interpreted as the $D_{s}(2^{1}S_{0})$ state.

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arXiv2021

Strong decays of the low-lying doubly bottom baryons

In this work, we adopt the $^3P_0$ model to investigate the strong decays of the low-lying doubly bottom baryons in the $j-j$ coupling scheme systematically. In this scheme, we construct the formulism of $^3P_0$ model under the spectator assumption, and then the heavy diquark symmetry is preserved automatically. Our results show that some of the $λ$-mode $Ξ_{bb}(1P)$ and $Ω_{bb}(1P)$ states are narrow, which have good potentials to be observed by future experiments. For the low-lying $ρ$-mode and $ρ$-$λ$ hybrid states, the Okubo-Zweig-Iizuka-allowed strong decays are highly suppressed and they should be extremely narrow. Future experiments can test our phenomenological predictions at the quark level.

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