arXiv subjects

Qing-Fu Song

Publications and source records attributed to Qing-Fu Song.

8 recordsLinked to original sources

arXiv2026

Exploring the $P$-wave bottom-strange molecular pentaquarks with the complex scaling method

In this work, we perform a systematic investigation of the $P$-wave $\Sigma_b K/\Lambda_b K^{*}/\Sigma_b K^{*}$ and $\Sigma_b\bar{K}/\Lambda_b\bar{K}^{*}/\Sigma_b\bar{K}^{*}$ systems for all possible $I(J^P)$ combinations. In contrast to our earlier study of the negative-parity sector [Eur. Phys. J. C \textbf{85}, 1026 (2025)], the positive-parity sector is dominated by resonances. For the coupled-channel $I(J^P)=1/2(1/2^+)$ $\Sigma_b K/\Lambda_b K^*/\Sigma_b K^*$ system, we predict a narrow resonance above the $\Sigma_b K$ threshold. In the $I(J^P)=1/2(3/2^+)$ $\Lambda_b K^*/\Sigma_b K^*$ system, a molecular resonance candidate is found above the $\Lambda_b K^*$ threshold. For the higher-isospin $I=3/2$ sector, resonances are identified in the $\Sigma_b K^*$ subsystem for both $J^P=1/2^+$ and $3/2^+$ cases, though both states exhibit relatively compact sizes. We also extend our analysis to the $\Sigma_b\bar{K}/\Lambda_b\bar{K}^{*}/\Sigma_b\bar{K}^{*}$ systems, where a cutoff-sensitive resonance is found in the $I(J^P)=1/2(1/2^+)$ configuration. A broad molecular resonance candidate is found below the $\Sigma_b\bar{K}^*$ threshold in the $I(J^P)=1/2(3/2^+)$ system. We hope that these predictions provide useful guidance for future experimental searches for bottom-strange molecular pentaquarks by LHCb.

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arXiv2025

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

We perform a systematic analysis of the low-lying $\Omega_c$ structures in a coupled-channel approach. The couplings between meson-baryon channels, $\Xi_c \bar K$, $\Xi_c^{\prime} \bar K$, $\Xi_c^{*} \bar K$, $\Omega_c\eta$ and $\Omega_c^{*}\eta$, and three-quark bare states $\Omega_c(1P_\lambda)$ are considered. We predict a bound state $\Omega_c(2954)$ below the $\Xi_c \bar K$ threshold with $(J^P,j)=(1/2^-,0)$, which can be studied in the final states of $\Omega_c^{(*)} \pi$ and $\Omega_c^{(*)} \gamma$. Also, the resonances $\Omega_c(3000)$ and $\Omega_c(3050)$ 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 $\Omega_c(2954)$ and measure the spin-parities of particles $\Omega_c(3000)$ and $\Omega_c(3050)$ 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

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 $Y_{b}(\Lambda_b,\Sigma_b) \bar K^{(*)}$ and $Y_{b} K^{(*)}$ systems. In particular, a bound state in the $I(J^P)=1/2(1/2^-)$ $\Sigma_{b}\bar{K}/\Lambda_{b}\bar{K}^*/\Sigma_{b}\bar{K}^*$ system may correspond to the particle $\Xi_{b}(6227)$. Meanwhile, the predicted bound state with $6303\sim6269~\rm{MeV}$ in the $I(J^P)=1/2(1/2^-)\Sigma_bK/\Lambda_bK^*/\Sigma_bK^*$ 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 $\Xi_b(6227)$. We highly hope that our proposals can offer helpful information for the future experimental searches.

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arXiv2024

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 $\lambda-$mode $\Xi_{cc/bb}(1P)$ and $\Omega_{cc/bb}(1P)$ states are relatively narrow, which are very likely to be discovered by future experiments. The light meson emissions for the low-lying $\rho-$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.

hep-ph↗

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 $\Lambda$. 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 $\eta_b(nS)/\Upsilon(nS)$ 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.

hep-ph↗

arXiv2023

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 Schr\"odinger equation. The lowest $\Xi_{bc}$, $\Xi_{bc}^\prime$, $\Omega_{bc}$, and $\Omega_{bc}^\prime$ 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 $\lambda-$mode $P-$wave bottom-charmed baryons are relatively narrow, which can be searched for in future experiments. For the low-lying $\rho-$mode and $\rho-\lambda$ 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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