arXiv subjects

Hui-Min Yang

Publications and source records attributed to Hui-Min Yang.

At least 19 recordsLinked to original sources

arXiv2026

Unified spectroscopy of $P$-wave flavor-sextet heavy baryons from QCD sum rules

We investigate the $P$-wave flavor-sextet charmed and bottom baryons within heavy quark effective theory. A key motivation is provided by the recent evidence for the $\Xi_c(2882)^0$, which completes a sequence of four narrow $\Xi_c$ structures together with the $\Xi_c(2923)^0$, $\Xi_c(2939)^0$, and $\Xi_c(2965)^0$. Their characteristic mass-splitting pattern closely parallels that of the $\Omega_c(3000)^0$, $\Omega_c(3050)^0$, $\Omega_c(3066)^0$, and $\Omega_c(3090)^0$ states, providing strong constraints on their spectroscopic assignments. We classify the seven $P$-wave states in each of the $\Sigma_Q$, $\Xi_Q^\prime$, and $\Omega_Q$ sectors ($Q=c,b$), calculate their masses and intra-doublet mass splittings using QCD sum rules, and study their strong decays using light-cone sum rules. Configuration mixing between states with the same quantum numbers is also investigated. The combined analysis favors a common interpretation of the four narrow $\Xi_c$ and the four lowest narrow $\Omega_c$ structures in terms of the corresponding $\lambda$-mode excitations. Extending the same framework to the bottom sector, we obtain a coherent picture of the observed $\Sigma_b$, $\Xi_b$, and $\Omega_b$ structures. In particular, the $\Sigma_b(6097)$, $\Xi_b(6227)$, and $\Omega_b(6350)$ structures may each contain an unresolved pair of nearby $P$-wave states. We also predict two additional $\Sigma_b$ states, two additional $\Xi_b^\prime$ states, and one additional $\Omega_b$ state, all of which are expected to be relatively narrow and remain to be identified experimentally.

hep-ph↗

arXiv2026

Quantum numbers of excited $\Xi_c^\prime$ and $\Omega_c$ baryons and the $P$-wave $\Sigma_c$ spectrum

Recent precision measurements of excited heavy baryons, combined with systematic theoretical studies, make it possible to resolve the fine structure of their spectra. We calculate the masses and strong-decay properties of the $P$-wave charmed baryons using QCD sum rules and light-cone sum rules within heavy quark effective theory (HQET). Although seven states are allowed in each flavor sector, we find that only four $\Sigma_c$, four $\Xi_c^\prime$, and five $\Omega_c$ states are expected to be experimentally resolvable. The similar mass-splitting patterns of $\Xi_c(2882)$, $\Xi_c(2923)$, $\Xi_c(2939)$, and $\Xi_c(2965)$ and of $\Omega_c(3000)$, $\Omega_c(3050)$, $\Omega_c(3066)$, and $\Omega_c(3090)$, together with our theoretical results, lead to the successive quantum-number assignments $J^P=1/2^-,3/2^-,3/2^-$, and $5/2^-$. We tentatively interpret $\Omega_c(3119)$ as a predominantly $\rho$-mode excitation with $J^P=3/2^-$. We also predict the masses, widths, and dominant decay modes of four resolvable $P$-wave $\Sigma_c$ states, which may overlap within the observed $\Sigma_c(2800)$ and $\Sigma_c(2900)$ structures. Precision spectroscopy of the narrow $\Xi_c$ and $\Omega_c$ states thus provides a route to resolving the $P$-wave $\Sigma_c$ spectrum.

hep-ph↗

arXiv2025

A short review on QCD sum rule studies of P-wave single heavy baryons

Over the past few decades, the study of singly heavy baryons has entered a golden era, with numerous excited states observed by experimental collaborations. Various theoretical approaches have been developed to investigate their properties, with the QCD sum rule method being one of the most widely applied. This paper provides a review of these QCD sum rule studies. Over the last ten years, we have systematically studied $P$-wave singly heavy baryons using QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. These $P$-wave singly heavy baryons can explain many excited heavy baryons, including the $\Lambda_c(2595)^+$, $\Lambda_c(2625)^+$, $\Xi_c(2790)^{0/+}$, $\Xi_c(2815)^{0/+}$, $\Sigma_c(2800)^0$, $\Xi_c(2882)^0$, $\Xi_c(2923)^0$, $\Xi_c(2939)^0$, $\Xi_c(2965)^0$, $\Omega_c(3000)^0$, $\Omega_c(3066)^0$, $\Omega_c(3090)^0$, $\Omega_c(3050)^0$, $\Omega_c(3119)^0$, $\Lambda_b(5912)^0$, $\Lambda_b(5920)^0$, $\Xi_b(6087)^0$, $\Xi_b(6095)^0/\Xi_b(6100)^-$, $\Sigma_b(6097)^\pm$, $\Xi_b(6227)^-$, $\Omega_b(6316)^-$, $\Omega_b(6330)^-$, $\Omega_b(6340)^-$, and $\Omega_b(6350)^-$, etc. Furthermore, we predict additional $P$-wave singly heavy baryons, including two $\Lambda_b$ states, two $\Xi_b$ states, three $\Sigma_b$ states, three $\Xi_b^\prime$ states, two $\Omega_b$ states, two $\Lambda_c$ states, two $\Xi_c$ states, three $\Sigma_c$ states, and one $\Omega_c$ state, all with relatively narrow decay widths, making them viable candidates for experimental observation. The study of singly heavy baryons is closely related to two meaningful questions:"What is the shortest possible lifetime of an observable particle?" and "How can one generally describe approximate (flavor) symmetries?".

hep-ph↗

arXiv2025

QCD sum rule study of topped mesons within heavy quark effective theory

Motivated by the recent CMS observation of a near-threshold enhancement in top quark pair production, we investigate a novel class of hadronic systems containing a single top quark: the topped mesons ($t\bar{q}$, with $\bar q = \bar u, \bar d, \bar s$). In contrast to the extensively studied toponium ($t\bar{t}$) system, analyzed primarily within perturbative QCD, topped mesons offer a complementary nonperturbative probe of QCD dynamics in the heavy quark limit. These states are expected to exhibit longer lifetimes and narrower decay widths than toponium, as only a single top quark undergoes weak decay. We employ QCD sum rules within the framework of heavy quark effective theory to study the structure and mass spectrum of ground-state topped mesons. Our analysis predicts masses near 173.1 GeV, approximately 0.5-0.6 GeV above the top quark pole mass. Compared with singly topped baryons ($tqq$, with $q = u, d, s$) studied concurrently in [arXiv:2507.05895], topped mesons have a simpler quark composition and more favorable decay channels (a topped meson is anticipated to decay weakly into a $\Upsilon$ meson and a charmed meson), enhancing their potential for both theoretical analysis and experimental discovery.

hep-ph↗

arXiv2025

Heavy flavored hydrogen molecule systems

This study provides a comprehensive analysis of $S$-wave exotic hydrogen-like three-body systems ($pp\mu^-$, $pp\tau^-$, $\mu^-\mu^-p$, $\tau^-\tau^-p$, $p\mu^-\tau^-$) with spin-parity $J^P = 1/2^+$ and $3/2^+$, and four-body systems ($pp\mu^-\mu^-$, $pp\tau^-\tau^-$) with $J^P = 0^+$, $1^+$, and $2^+$. We use complex scaling and Gaussian expansion methods to solve the complex-scaled Schr\"{o}dinger equation and obtain possible bound and quasi-bound states. The resulting binding energies range from $-33.8$~keV to $-340$~eV. Notably, we present the first theoretical estimation of the bound-state energy levels of $pp\mu^-\mu^-$ and $pp\tau^-\tau^-$, which is of significant importance for understanding exotic few-body Coulomb systems. We further analyze spin configurations and root-mean-square radii to elucidate the spatial structure of these bound and quasi-bound states. Our results reveal that $K$-type spatial configurations play a crucial role in accurately describing bound and quasi-bound states in the hydrogen-molecule-like systems $pp\mu^-\mu^-$ and $pp\tau^-\tau^-$. Incorporating $K$-type configurations significantly alters the mass spectra of these states. Future muon colliders and muon facilities may offer promising platforms for the possible copious production of such heavy flavored hydrogen molecules and molecular ions. For instance, scattering processes such as $2\mu^- + \mathrm{H_2} \to \mathrm{H_{2\mu}} + 2e^-$, $\mu^- + \mathrm{H_2} \to \mathrm{H_{\mu e}} + e^-$, and $\mu^- + \mathrm{H_2^+} \to \mathrm{H_{2\mu}^+} + e^-$ could be utilized, facilitating detailed studies of intriguing states such as $\mathrm{H_{2\mu}}$, $\mathrm{H_{\mu e}}$, and $\mathrm{H_{2\mu}^+}$.

physics.atom-ph↗

arXiv2025

Light hybrid baryons in QCD sum rules

We have calculated the mass spectra of nucleon and delta hybrid baryons with both positive-parity and negative-parity by using the method of QCD sum rules. We predicte that the lowest-lying hybrid baryons are the negative-parity $N_{1/2^-}$ and $\Delta_{1/2^-}$ states, while the positive-parity ones are much heavier. We suggest to search for these light hybrid baryons via the $\chi_{cJ}/\Upsilon$ decay processes in the future.

hep-ph↗

arXiv2025

Radiative decays of $P$-wave charmed baryons in the $SU(3)$ flavor $\bf6_F$ representation

We perform a comprehensive investigation of the radiative decays of $P$-wave charmed baryons in the $SU(3)$ flavor $\mathbf{6}_F$ representation, employing the light-cone QCD sum rule approach within the framework of heavy quark effective theory. We analyze their electromagnetic transitions into ground-state charmed baryons via photon emission. When combined with the mass spectra and strong decay properties previously studied in Ref.~\cite{Yang:2021lce}, our results constitute a systematic and complete QCD sum rule analysis of the $P$-wave singly charmed baryons within the framework of heavy quark effective theory. As summarized in Table~\ref{tab:result}, several excited charmed baryons are found to possess suppressed strong decay widths, thereby rendering their radiative decay channels particularly significant for experimental identification and theoretical understanding.

hep-ph↗

arXiv2025

Investigating charmed hybrid baryons via QCD sum rules

We investigate charmed hybrid baryons using the QCD sum rule method within the framework of heavy quark effective theory. We construct twenty-eight interpolating currents for charmed hybrid baryons, seven of which are employed in QCD sum rule analyses of nineteen states with quark-gluon configurations $qqcg$, $qscg$, and $sscg$ ($q = u/d$). The masses of the lowest-lying charmed hybrid baryons in the $SU(3)$ flavor $\mathbf{6}_F$ representation are calculated to be $M_{\Sigma_{cg}(1/2^+)} = 3.36^{+0.27}_{-0.26}~\rm{GeV}$, $M_{\Xi^\prime_{cg}(1/2^+)} = 3.59\pm 0.20~\rm{GeV}$, and $M_{\Omega_{cg}(1/2^+)} = 3.82\pm 0.21~\rm{GeV}$. We propose that future experiments search for these states via their $P$-wave decay channels $ND^{(*)}$, $\Lambda D^{(*)}$, and $\Xi D^{(*)}$, respectively. Such investigations would provide valuable insight into the role of gluonic excitations in hadron structure.

hep-ph↗

arXiv2025

Triply heavy tetraquark states with different flavors

We investigate the $S$-wave triply heavy tetraquark systems, including the $QQ^{(\prime)}\bar Q^{(\prime)}\bar q$ and $QQ^{(\prime)}\bar Q^{(\prime)}\bar s$ configurations ($Q^{(\prime)} = c, b$, $q = u, d$) with spin-parity $J^P = 0^+$, $1^+$, and $2^+$, within the framework of the constituent quark model. We construct the wave functions for these systems, incorporating complete color-spin wave functions and spatial wave functions with three different Jacobi coordinate configurations. We use complex scaling and Gaussian expansion method to solve the complex-scaled four-body Schr\"{o}dinger equation and obtain possible exotic states. To analyze the spatial properties of the tetraquark states, we compute the root-mean-square (rms) radii, which help distinguish between meson-molecular and compact tetraquark states. We find that there do not exist any bound states in the $QQ^{(\prime)}\bar Q^{(\prime)}\bar q$ and $QQ^{(\prime)}\bar Q^{(\prime)}\bar s$ systems. However, we identify a possible molecular resonant state $T_{3c,2}(5819)$ in the $cc\bar c\bar q$ system with spin-parity $J^P = 2^+$, which lies slightly above the $J/\psi D^*(2S)$ threshold and has a large rms radius around 2.2 fm. Furthermore, we obtain a series of compact resonant states, some of which exhibit spatial structure similar to the tritium atom in QED, where the light quark circles around the cluster of three heavy quarks. The lowest resonant state in the triply heavy systems has a mass of $5634$ MeV, a width of $16$ MeV and spin-parity $J^P=1^+$. We suggest searching for this state in the $J/\psi D$, $\eta_c D^*$, and $J/\psi D^*$ decay channels.

hep-ph↗

arXiv2024

Predictions of masses for light hybrid baryons

Within the method of parity-projected QCD sum rules, we study the mass spectra of light hybrid baryons with $I(J^{P})=1/2(1/2^{\pm}), 3/2(1/2^{\pm}), 1/2(3/2^{\pm}), 3/2(3/2^{\pm})$ by constructing the local $qqqg$ interpolating currents. We calculate the correlation functions up to dimension eight condensates at the leading order of $\alpha_{s}$. The stable QCD Lapalce sum rules can be established for the positive-parity $N_{1/2^+}, \Delta_{3/2^+}, \Delta_{1/2^+}$ and negative-parity $N_{1/2^-}, N_{3/2^-}, \Delta_{1/2^-}$ channels to extract their mass spectra. The lowest-lying hybrid baryons are predicted to be the positive-parity $N_{1/2^+}$ state around 2.01 GeV. These hybrid baryons mainly decay into conventional baryon plus meson final states. We propose to search for the light hybrid baryons through the $\Upsilon/\psi(3686)$ decays via the three-gluon emission mechanism in BESIII and BelleII experiments. Hopefully our studies of the light hybrid baryons will be useful for understanding the excited baryon spectrum and the behavior of gluonic degrees of freedom in QCD.

hep-ph↗

arXiv2024

Toponium: the smallest bound state and simplest hadron in quantum mechanics

We explore toponium, the smallest known quantum bound state of a top quark and its antiparticle, bound by the strong force. With a Bohr radius of $8\times 10^{-18}$~m and a lifetime of $2.5 \times 10^{-25}$~s, toponium uniquely probes microphysics. Unlike all other hadrons, it is governed by ultraviolet freedom. This distinction offers novel insights into quantum chromodynamics. Our analysis reveals a toponium signal exceeding $5\sigma$ in the distribution of the cross section ratio between $e^+e^- \rightarrow b\bar{b}$ and $e^+e^- \rightarrow q\bar{q}$ ($q=b,c,s,d,u$), based on 400~fb$^{-1}$ of data collected at $\sqrt{s}\approx 341~{\rm GeV}$. This discovery enables a top quark mass measurement with an uncertainty reduced by a factor of ten compared to current precision levels. Moreover, this method improves the systematic uncertainty by at least a factor of 2.7 compared to any other possible methods.

hep-ph↗

arXiv2024

Radiative decays of $P$-wave bottom baryons from light-cone sum rules

We carry out a comprehensive investigation on the radiative decays of $P$-wave bottom baryons using the light-cone sum rule method. We analyze their electromagnetic transitions into ground-state bottom baryons together with a photon. Together with their mass spectra and strong decays investigated in Refs. \cite{Yang:2020zrh,Tan:2023opd}, a rather complete QCD sum rule study has been done to understand the $P$-wave singly bottom baryons within the framework of heavy quark effective theory. As summarized in Tables~\ref{tab:candidate}/\ref{tab:candidate6f}, some $P$-wave bottom baryons have limited strong decay widths so that their radiative decay widths become non-negligible. We propose to study these excited bottom baryons and their radiative decays in the future Belle-II, BESIII, and LHCb experiments.

hep-ph↗

arXiv2023

Predicted $\Xi_b(6087)^0$ and further predictions

The methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory have been widely applied to study the singly heavy baryons, and especially, we have applied these methods to predict not only the mass and width of the $\Xi_b(6087)^0$ recently discovered by LHCb, but also its observation channel and its mass difference from the $\Xi_b(6100)^-$. We apply the same approach to perform a complete study on the $P$-wave bottom baryons of the $SU(3)$ flavor $\mathbf{\bar 3}_F$ and investigate their fine structure. Besides the $\Lambda_b(5912)^0$, $\Lambda_b(5920)^0$, $\Xi_b(6087)^0$, and $\Xi_b(6100)^-$, our results suggest the existence of the other two $\Lambda_b$ and two $\Xi_b$ baryons, whose widths are limited. They are the $\Lambda_b(J^P = 3/2^-)$ with the mass and width about $(5.93^{+0.13}_{-0.13}~{\rm GeV},\,0.0^{+12.0}_{-~0.0}~{\rm MeV})$, the $\Lambda_b(5/2^-)$ with $(5.94^{+0.13}_{-0.13}~{\rm GeV},\,\approx0~{\rm MeV})$, the $\Xi_b(3/2^-)$ with $(6.10^{+0.15}_{-0.10}~{\rm GeV},\,1.4{^{+11.6}_{-~1.4}}~{\rm MeV})$, and the $\Xi_b(5/2^-)$ with $(6.11^{+0.15}_{-0.10}~{\rm GeV},\,1.0{^{+7.4}_{-1.0}}~{\rm MeV})$. Their mass splittings are calculated to be $M_{\Lambda_b(5/2^-)} - M_{\Lambda_b(3/2^-)} = 17\pm7~{\rm MeV}$ and $M_{\Xi_b(5/2^-)} - M_{\Xi_b(3/2^-)} = 14\pm7~{\rm MeV}$. All these baryons are explained as the $P$-wave bottom baryons of the $\rho$-mode, where the orbital excitation is between the two light quarks. However, the existence of this mode is still controversial, so their experimental searches can verify both our approach and the existence of the $\rho$-mode, which can significantly improve our understanding on the internal structure of hadrons.

hep-ph↗

arXiv2023

2$P$-wave charmed baryons from QCD sum rules

We conduct an investigation on the $1P$- and $2P$-wave charmed baryons using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the $\Lambda_c(2910)^+$, $\Lambda_c(2940)^+$, and $\Xi_c(3123)^+$ can be well interpreted as the $2P$-wave charmed baryons of $J^P=1/2^-$ and $3/2^-$, belonging to the $SU(3)$ flavor $\mathbf{\bar 3}_F$ representation. Moreover, the $\Xi_c(3123)^+$ possesses a partner state characterized by $J^P=1/2^-$, denoted as $\Xi_c(1/2^-,2P)$. Our analysis predicts its mass and width to be $m_{\Xi_c(1/2^-,2P)} - m_{\Xi_c(3123)^+} = -18\pm{7}$MeV and $\Gamma_{\Xi_c(2P,1/2^-)}=31^{+170}_{-27}$MeV, with $m_{\Xi_c(3123)^+} = 3122.9\pm{1.3}$MeV. We propose to search for it in the $\Xi_c(1/2^-,2P)\to \Sigma_c K$ decay channel.

hep-ph↗

arXiv2022

Identifying the $Ξ_b(6100)$ as the $P$-wave bottom baryon of $J^P=3/2^-$

We study the $Ξ_b(6100)$ using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the $Ξ_b(6100)$ can be well interpreted as the $P$-wave bottom baryon of $J^P=3/2^-$, belonging to the $SU(3)$ flavor $\mathbf{\bar 3}_F$ representation. It has a partner state of $J^P=1/2^-$, labelled as $Ξ_b(1/2^-)$, whose mass and width are predicted to be $m_{Ξ_b(1/2^-)}=6.08^{+0.13}_{-0.11}$~GeV and $Γ_{Ξ_b(1/2^-)}=4^{+29}_{-~4}$~MeV, with the mass splitting $ΔM=m_{Ξ_b(6100)}-m_{Ξ_b(1/2^-)}=9\pm3$~MeV. We propose to search for it in the $Ξ_c({1/2}^-)\to Ξ_b^{\prime}π$ decay channel. Our results also suggest that the $Λ_b(5912)$ and $Λ_b(5920)$ are their partner states with $J^P=1/2^-$ and $3/2^-$ respectively, and moreover, the $Λ_c(2595)$, $Λ_c(2625)$, $Ξ_c(2790)$, and $Ξ_c(2815)$ are their charmed partner states.

hep-ph↗

arXiv2022

Roles of $a_0(980)$, $Λ(1670)$, and $Σ(1385)$ in the $Λ_c^+ \to ηΛπ^+$ decay

Recently, the Belle Collaboration has measured the $Λ_c^+ \to ηΛπ^+$ decay and reported the $ηΛ$ and $Λπ^+ $ invariant mass distributions, which show the clear signals of the resonances $Λ(1670)$ and $Σ(1385)$, respectively. Based on our previous works [Eur. Phys. J. C 76 (2016) 496 and Phys. Rev. D 95 (2017) 074024], we re-analyze this process by considering the $S$-wave $ηΛ$ and $ηπ^+$ final state interactions within the chiral unitary approach, which dynamically generate the $Λ(1670)$ and $a_0(980)$, respectively. Our results are in good agreement with the Belle measurements, which supports the molecular nature of the $Λ(1670)$ and $a_0(980)$. In addition, the $ηπ^+$ invariant mass distributions are also computed and a cusp structure of $a_0(980)$ is cleary shown around the $K\bar{K}$ mass threshold.

hep-ph↗

arXiv2021

$P$-wave charmed baryons of the $SU(3)$ flavor $\mathbf{6}_F$

We use QCD sum rules to study mass spectra of $P$-wave charmed baryons of the $SU(3)$ flavor $\mathbf{6}_F$. We also use light-cone sum rules to study their $S$- and $D$-wave decays into ground-state charmed baryons together with light pseudoscalar and vector mesons. We work within the framework of heavy quark effective theory, and we also consider the mixing effect. Our results can explain many excited charmed baryons as a whole, including the $Σ_c(2800)^0$, $Ξ_c(2923)^0$, $Ξ_c(2939)^0$, $Ξ_{c}(2965)^{0}$, $Ω_c(3000)^0$, $Ω_c(3050)^0$, $Ω_c(3066)^0$, $Ω_c(3090)^0$, and $Ω_c(3119)^0$. Their masses, mass splittings within the same multiplets, and decay properties are extracted for future experimental searches.

hep-ph↗

arXiv2020

Identifying the $Ξ_c^0$ baryons observed by LHCb as $P$-wave $Ξ_c^\prime$ baryons

We systematically study mass spectra and decay properties of $P$-wave $Ξ_c^\prime$ baryons of the $SU(3)$ flavor $\mathbf{6}_F$, using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the three excited $Ξ_c^0$ baryons recently observed by LHCb can be well explained as $P$-wave $Ξ_c^\prime$ baryons: the $Ξ_c(2923)^0$ and $Ξ_c(2939)^0$ are partner states of $J^P = 1/2^-$ and $3/2^-$ respectively, both of which contain one $λ$-mode orbital excitation; the $Ξ_c(2965)^0$ has $J^P = 3/2^-$, and also contains one $λ$-mode orbital excitation. We propose to search for another $P$-wave $Ξ_c^\prime$ state of $J^P = 5/2^-$ in the $Λ_c K/Ξ_c π$ mass spectral in future experiments. Its mass is about $56^{+30}_{-35}$ MeV larger than the $Ξ_c(2965)^0$, and its width is about $18.1^{+19.7}_{-~8.3}$ MeV.

hep-ph↗