arXiv subjects

Shi-Lin Zhu

Publications and source records attributed to Shi-Lin Zhu.

At least 127 records · Page 7Linked to original sources

arXiv2019

Light pseudoscalar meson and doubly charmed baryon scattering lengths with heavy diquark-antiquark symmetry

We adopt the heavy baryon chiral perturbation theory (HBChPT) to calculate the scattering lengths of $ϕB_{cc}^{(*)}$ up to $\mathcal{O}(p^3)$, where $ϕ$ is the pseudoscalar mesons. The recoil effect and the mass splitting between the spin-$1\over 2$ and spin-$3\over 2$ doubly charmed baryons are included. In order to give the numerical results, we construct the chiral Lagrangians with heavy diquark-antiquark (HDA) symmetry in a formally covariant approach. Then, we relate the low energy constants (LECs) of the doubly charmed baryons to those of $D^{(*)}$ mesons. The LECs for the $ϕD^{(*)}$ scattering are estimated in two scenarios, fitting lattice QCD results and using the resonance saturation model. The chiral convergence of the first scenario is not good enough due to the the large strange quark mass and the presence of the possible bound states, virtual states and resonance. The final results for two scenarios are consistent with each other. The interaction for the $[πΞ^{(*)}_{cc}]^{(1/2)}$, $[KΞ^{(*)}_{cc}]^{(0)}$, $[KΩ^{(*)}_{cc}]^{(1/2)}$, $[ηΞ^{(*)}_{cc}]^{(1/2)}$, $[ηΩ^{(*)}_{cc}]^{(0)}$ and $[\bar{K}Ξ^{(*)}_{cc}]^{(0)}$ channels are attractive. The most attractive channel $[\bar{K}Ξ^{(*)}_{cc}]^{(0)}$ may help to form the partner states of the $D_{s0}^*(2317)$ ($D_{s1}(2460)$) in the doubly heavy sector.

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arXiv2019

Strong LHCb evidence supporting the existence of the hidden-charm molecular pentaquarks

On March 26th, 2019, at the Rencontres de Moriond QCD conference, the LHCb Collaboration reported the observation of three new pentaquarks, namely $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$, which are consistent with the loosely bound molecular hidden-charm pentaquark states composed of an S-wave charmed baryon $Σ_c$ and an S-wave anti-charmed meson ($\bar{D}, \bar{D}^*$). In this work, we present a direct calculation by the one-boson-exchange (OBE) model and demonstrate explicitly that the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ do correspond to the loosely bound $Σ_c\bar{D}$ with $(I=1/2,J^P=1/2^-)$, $Σ_c\bar{D}^*$ with $(I=1/2,J^P=1/2^-)$ and $Σ_c\bar{D}^*$ with $(I=1/2,J^P=3/2^-)$, respectively.

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arXiv2019

Possible Molecular States Composed of Doubly Charmed Baryons with Couple-channel Effect

We systematically investigate the possible molecular states composed of (1) two spin-$\frac{3}{2}$ doubly charmed baryons, and (2) a pair of spin-$\frac{3}{2}$ and spin-$\frac{1}{2}$ doubly charmed baryons. The one-boson-exchange (OBE) model is used to describe the potential between two baryons. The channel mixing effect is considered for the systems with the same quantum number $(I(J^P))$ but different total spin ($S$) and orbital angular momenta ($L$). We also study the channel mixing effect among the systems composed of various doubly charmed baryons if they have the same quantum number. Many of the systems are good candidates of molecular states.

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arXiv2019

The hidden charm pentaquark states and $Σ_c\bar{D}^{(*)}$ interaction in chiral perturbation theory

In this work, we employ the heavy hadron chiral perturbation theory (HHChPT) to calculate the $Σ_c\bar{D}^{(*)}$ potentials to the next-to-leading order. The contact, the one-pion exchange and the two-pion exchange interactions are included. Besides, the mass splittings between the heavy quark spin symmetry (HQSS) multiplets are kept in calculations. Our result shows that neglecting the heavy quark symmetry (HQS) violation effect may be misleading to predict the potentials between the charmed hadrons. We perform numerical analysis with three scenarios. In the first scenario, we relate the low-energy constants (LECs) in the contact terms of $Σ_c\bar{D}^{(*)}$ to those of nucleon systems, and reproduce the $P_c(4312)$ and $P_c(4440)$ as loosely bound states. In the second scenario, we vary the unknown LECs and find a small parameter region in which $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ can coexist as molecular states. In the third scenario, we include the coupled-channel effect on the basis of scenario II, and notice that the three $P_c$ states can be reproduced as molecular states simultaneously in a large region of parameters. Our analytical results can be used for the chiral extrapolations in lattice QCD. With the lattice QCD results in the future as inputs, the identification of the $P_c$ states and predictions for other systems would be more reliable.

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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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arXiv2019

Pentaquark and Tetraquark states

The past seventeen years have witnessed tremendous progress on the experimental and theoretical explorations of the multiquark states. The hidden-charm and hidden-bottom multiquark systems were reviewed extensively in [Phys. Rept. 639 (2016) 1-121]. In this article, we shall update the experimental and theoretical efforts on the hidden heavy flavor multiquark systems in the past three years. Especially the LHCb collaboration not only confirmed the existence of the hidden-charm pentaquarks but also provided strong evidence of the molecular picture. Besides the well-known $XYZ$ and $P_c$ states, we shall discuss more interesting tetraquark and pentaquark systems either with one, two, three or even four heavy quarks. Some very intriguing states include the fully heavy exotic tetraquark states $QQ\bar Q\bar Q$ and doubly heavy tetraquark states $QQ\bar q \bar q$, where $Q$ is a heavy quark. The $QQ\bar Q\bar Q$ states may be produced at LHC while the $QQ\bar q \bar q$ system may be searched for at BelleII and LHCb. Moreover, we shall pay special attention to various theoretical schemes. We shall emphasize the model-independent predictions of various models which are truly/closely related to Quantum Chromodynamics (QCD). There have also accumulated many lattice QCD simulations through multiple channel scattering on the lattice in recent years, which provide deep insights into the underlying structure/dynamics of the $XYZ$ states. In terms of the recent $P_c$ states, the lattice simulations of the charmed baryon and anti-charmed meson scattering are badly needed. We shall also discuss some important states which may be searched for at BESIII, BelleII and LHCb in the coming years.

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arXiv2019

Revisiting hidden-charm pentaquarks from QCD sum rules

We revisit the hidden-charm pentaquark states $P_c(4380)$ and $P_c(4450)$ using the method of QCD sum rules by requiring the pole contribution to be larger than or around 30\% to better insure the one-pole parametrization to be valid. We find two mixing currents and our results suggest that the $P_c(4380)$ and $P_c(4450)$ can be identified as hidden-charm pentaquark states having $J^P=3/2^-$ and $5/2^+$, respectively, while there still exist other possible spin-parity assignments, such as $J^P=3/2^+$ and $J^P=5/2^-$, which needs to be clarified in further theoretical and experimental studies.

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arXiv2019

Hadronic Molecular States Composed of Spin-$3\over 2$ Singly Charmed Baryons

We investigate the possible deuteron-like molecules composed of a pair of charmed spin-$\frac{3}{2}$ baryons, or one charmed baryon and one charmed antibaryon within the one-boson-exchange (OBE) model. For the spin singlet and triplet systems, we consider the couple channel effect between systems with different orbital angular momentum. Most of the systems have binding solutions. The couple channel effect plays a significant role in the formation of some loosely bound states. The possible molecular states of $Ω_c^*Ω_c^*$ and $Ω_c^*\barΩ_c^*$ might be stable once produced.

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arXiv2019

Systematic studies of charmonium-, bottomonium-, and $B_c$-like tetraquark states

We study the mass splittings of $Q_1q_2\bar{Q}_3\bar{q}_4$ ($Q=c,b$, $q=u,d,s$) tetraquark states with chromomagnetic interactions between their quark components. Assuming that $X(4140)$ is the lowest $J^{PC}=1^{++}$ $cs\bar{c}\bar{s}$ tetraquark, we estimate the masses of the other tetraquark states. From the obtained masses and defined measure reflecting effective quark interactions, we find the following assignments for several exotic states: (1) both $X(3860)$ and the newly observed $Z_c(4100)$ seem to be $0^{++}$ $cn\bar{c}\bar{n}$ tetraquarks; (2) $Z_c(4200)$ is probably a $1^{+-}$ $cn\bar{c}\bar{n}$ tetraquark; (3) $Z_c(3900)$, $X(3940)$, and $X(4160)$ are unlikely compact tetraquarks; (4) $Z_c(4020)$ is unlikely a compact tetraquark, but seems the hidden-charm correspondence of $Z_b(10650)$ with $J^{PC}=1^{+-}$; and (5) $Z_c(4250)$ can be a tetraquark candidate but the quantum numbers cannot be assigned at present. We hope further studies may check the predictions and assignments given here.

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arXiv2018

Magnetic moments of the spin-${3\over 2}$ singly heavy baryons

We calculate the magnetic moments of spin-$3\over 2$ singly charmed baryons in the heavy baryon chiral perturbation theory (HBChPT). The analytical expressions are given up to $\mathcal{O}(p^3)$. The heavy quark symmetry is used to reduce the number of low energy constants (LECs). With the lattice QCD simulation data as the magnetic moments of the charmed baryons, the numerical results are given up to $\mathcal{O}(p^3)$ in three scenarios. In the first scenario, we use the results in the quark model as the leading order input. In the second scenario, we use the heavy quark symmetry and neglect the contribution of heavy quark. In the third scenario, the heavy quark contribution is considered on the basis of the scenario II and the magnetic moments of singly bottom baryons are given as a by-product.

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arXiv2018

The radiative decays of the singly heavy baryons in chiral perturbation theory

In the framework of the heavy baryon chiral perturbation theory (HBChPT), we calculate the radiative decay amplitudes of the singly heavy baryons up to the next-to-next-to-leading order (NNLO). In the numerical analysis, we adopt the heavy quark symmetry to relate some low energy constants (LECs) with those LECs in the calculation of the magnetic moments. We use the results from the lattice QCD simulation as input. With a set of unified LECs, we obtain the numerical (transition) magnetic moments and radiative decay widths. We give the numerical results for the spin-$1\over 2$ sextet to the spin-$1\over 2$ antitriplet up to the next-to-leading order (NLO). The nonvanishing $Γ(Ξ_c^{'0} \rightarrow Ξ^0_cγ)$ and $Γ(Ξ_c^{*0} \rightarrow Ξ^0_c γ)$ solely arise from the U-spin symmetry breaking, and do not depend on the lattice QCD inputs up to NLO. We also systematically give the numerical analysis of the magnetic moments of the spin-$1\over 2$, spin-$3\over 2$ sextet and their radiative decay widths up to NNLO. In the heavy quark limit, the radiative decays between the sextet states happen through the magnetic dipole (M1) transitions, while the electric quadrupole (E2) transition does not contribute. We also extend the same analysis to the single bottom baryons.

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arXiv2018

Surveying exotic pentaquarks with the typical $QQqq\bar{q}$ configuration

As a hot issue, exploring exotic pentaquarks is full of challenges and opportunities for both theorist and experimentalist. In this work, we focus on a type of pentaquark with the $QQqq\bar{q}$ ($Q=b,c$; $q=u,d,s$) configuration, where their mass spectrum is estimated systematically. Especially, our result indicates that there may exist some stable or narrow exotic pentaquark states. Obviously, our study may provides valuable information for further experimental search for the $QQqq\bar{q}$ pentaquarks. With the running of LHCb and forthcoming Belle II, we have a reason to believe that these predictions present here can be tested.

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arXiv2018

Magnetic moments of the spin-$1\over 2$ singly charmed baryons in chiral perturbation theory

We systematically derive the analytical expressions of the magnetic moments of the spin-$1\over 2$ singly charmed baryons to the next-to-next-to-leading order in the heavy baryon chiral perturbation theory (HBChPT). We discuss the analytical relations between the magnetic moments. We estimate the-low energy constants (LECs) in two scenarios. In the first scenario, we use the quark model and Lattice QCD simulation results as input. In the second scenario, the heavy quark symmetry is adopted to reduce the number of the independent LECs, which are then fitted using the data from the Lattice QCD simulations. We give the numerical results to the next-to-leading order for the antitriplet charmed baryons and to the next-to-next-to-leading order for the sextet states.

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arXiv2018

Magnetic moments of the spin-${3\over 2}$ doubly heavy baryons

In this work, we investigate the chiral corrections to the magnetic moments of the spin-$3\over 2$ doubly charmed baryons systematically up to next-to-next-to-leading order with the heavy baryon chiral perturbation theory. The numerical results are given up to next-to-leading order: $μ_{Ξ^{*++}_{cc}}=1.72μ_{N}$, $μ_{Ξ^{*+}_{cc}}=-0.09μ_{N}$, $μ_{Ω^{*+}_{cc}}=0.99μ_{N}$. As a by-product, we have also calculated the magnetic moments of the spin-$3\over 2$ doubly bottom baryons and charmed bottom baryons: $μ_{Ξ^{*0}_{bb}}=0.63μ_{N}$, $μ_{Ξ^{*-}_{bb}}=-0.79μ_{N}$, $μ_{Ω^{*-}_{bb}}=0.12μ_{N}$, $μ_{Ξ^{*+}_{bc}}=1.12μ_{N}$, $μ_{Ξ^{*0}_{bc}}=-0.40μ_{N}$, $μ_{Ω^{*0}_{bc}}=0.56μ_{N}$.

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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

A possible partner state of the $Y(2175)$

We study the $Y(2175)$ using the method of QCD sum rules. There are two independent $ss\bar s\bar s$ interpolating currents with $J^{PC} = 1^{--}$, and we calculate both their diagonal and off-diagonal correlation functions. We obtain two new currents which do not strongly correlate to each other, so they may couple to two different physical states: one of them couples to the $Y(2175)$, while the other may couple to another state whose mass is about $71 ^{+172}_{-~48}$ MeV larger. Evidences of the latter state can be found in the BaBar, BESII, Belle, and BESIII experiments.

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arXiv2018

Heavy-flavored tetraquark states with the $QQ\bar{Q}\bar{Q}$ configuration

In the framework of the color-magnetic interaction, we systematically investigate the mass spectrum of the tetraquark states composed of four heavy quarks with the $QQ\bar Q\bar Q$ configuration in this work. We also show their strong decay patterns. Stable or narrow states in the $bb\bar{b}\bar{c}$ and $bc\bar{b}\bar{c}$ systems are found to be possible. We hope the studies shall be helpful to the experimental search for heavy-full exotic tetraquark states.

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arXiv2018

Doubly hidden-charm/bottom $QQ\bar Q\bar Q$ tetraquark states

We study the mass spectra for the $cc\bar c\bar c$ and $bb\bar b\bar b$ tetraquark states by developing a moment sum rule method. Our results show that the $bb\bar b\bar b$ tetraquarks lie below the threshold of $η_b(1S)η_b(1S)$. They are probably stable and very narrow. The masses for the doubly hidden-charm states $cc\bar c\bar c$ are higher than the spontaneous dissociation thresholds of two charmonium mesons. We suggest to search for such states in the $J/ψJ/ψ$ and $η_c(1S)η_c(1S)$ channels.

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