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Zhi-Gang Wang

Publications and source records attributed to Zhi-Gang Wang.

At least 109 records · Page 6Linked to original sources
arXiv2022

Analysis of the bottom-charm baryon states with QCD sum rules

In this work, we explore the ground state mass spectrum of the bottom-charm baryon states in the framework of the QCD sum rules in a comprehensive way. In calculations, we distinguish the contributions of the positive-parity and negative-parity baryon states unambiguously, and investigate the energy scale dependence of the QCD sum rules in details and observe that the acceptable energy scales are $μ=2.0\sim 2.8\,\rm{GeV}$, while the best energy scale is $μ=2.0\,\rm{GeV}$. The predictions can be confronted to the experimental data in the future and shed light on the QCD low energy dynamics.

hep-ph↗
arXiv2022

Analysis of the pseudoscalar hidden-charm tetraquark states with the QCD sum rules

In this work, we take all the color-antitriplet diquarks, such as the scalar, pseudoscalar, vector, axialvector and tensor diquarks, as the basic constituents to construct the local pseudoscalar four-quark currents without importing the explicit P-waves to implement the negative-parity, and investigate the mass spectroscopy of the pseudoscalar hidden-charm tetraquark states without strange, with strange and with hidden-strange in the framework of the QCD sum rules in a consistent and comprehensive way. We obtain the lowest mass $4.56\pm0.08\,\rm{GeV}$ for the pseudoscalar tetraquark state with the symbolic quark constituents $c\bar{c}u\bar{d}$, which is much larger than the experimental value $4239\pm18{}^{+45}_{-10}\,\rm{MeV}$ extracted by the LHCb collaboration.

hep-ph↗
arXiv2022

Comment on "$Z_c$-like spectra from QCD Laplace sum rules at NLO"

In Phys. Rev. {\bf D103} (2021) 074015 (arXiv:2101.07281), huge (or largest) mass gaps between the ground states and first radial excited states for the tetraquark molecular states are obtained, $Δ=1.70\sim 2.35\,\rm{GeV}$. We explore the problems in the operator product expansion, Borel windows, etc, in details.

hep-ph↗
arXiv2021

Some properties of certain close-to-convex harmonic mappings

In this paper, we determine the sharp estimates for Toeplitz determinants of a subclass of close-to-convex harmonic mappings. Moreover, we obtain an improved version of Bohr's inequalities for a subclass of close-to-convex harmonic mappings, whose analytic parts are Ma-Minda convex functions.

math.CV↗
arXiv2021

Assignments of the $X(4140)$, $X(4500)$, $X(4630)$ and $X(4685)$ based on the QCD sum rules

In this article, we take into account our previous calculations based on the QCD sum rules, and tentatively assign the $X(4630)$ as the $D_s^*\bar{D}_{s1}-D_{s1}\bar{D}_s^*$ tetraquark molecular state or $[cs]_P[\bar{c}\bar{s}]_A+[cs]_A[\bar{c}\bar{s}]_P$ tetraquark state with the $J^{PC}=1^{-+}$, and assign the $X(3915)$ and $X(4500)$ as the 1S and 2S $[cs]_A[\bar{c}\bar{s}]_A$ tetraquark states respectively with the $J^{PC}=0^{++}$. Then we extend our previous works to investigate the LHCb's new tetraquark candidate $X(4685)$ as the first radial excited state of the $X(4140)$ with the QCD sum rules, and obtain the mass $M_{X}=4.70\pm0.12\,\rm{GeV}$, which is in very good agreement with the experimental value $4684 \pm 7 {}^{+13}_{-16}\,\rm{MeV}$. Furthermore, we investigate the two-meson scattering state contributions in details, and observe that the two-meson scattering states alone cannot saturate the QCD sum rules, the contributions of the tetraquark states play an un-substitutable role, we can saturate the QCD sum rules with or without the two-meson scattering states.

hep-ph↗
arXiv2021

Does vacuum saturation work for the higher dimensional vacuum condensates in the QCD sum rules?

In the QCD sum rules for the tetraquark (molecular) states, the higher dimensional vacuum condensates play an important role in extracting the tetraquark masses. We carry out the operator product expansion up to the vacuum condensates of dimension-10 and observe that the vacuum condensates of dimensions $6$, $8$ and $10$ have the same expressions but opposite signs for the $Cγ_5\otimes γ_μC$-type and $C\otimes γ_μC$ type four-quark currents, which make their influences distinguishable, and they are excellent channels to examine the vacuum saturation approximation. We introduce a parameter $κ$ to parameterize the derivation from the vacuum saturation or factorization approximation, and choose two sets parameters to examine the influences on the predicted tetraquark masses, which can be confronted to the experimental data in the future. In all the channels, smaller value of the $κ$ leads to better convergent behavior in the operator product expansion, which favors the vacuum saturation approximation.

hep-ph↗
arXiv2021

Analysis of the vector hidden-charm tetraquark states without explicit P-waves via the QCD sum rules

In the present work, we adopt the scalar, pseudoscalar, vector, axialvector and tensor (anti)diquark operators as the elementary building blocks to construct vector and tensor local four-quark currents without introducing explicit P-waves, and explore the mass spectrum of the vector hidden-charm tetraquark states via the QCD sum rules comprehensively, and revisit the interpretations of the existing $Y$ states in the scenario of vector tetraquark states. We resort to the energy scale formula to enhance the pole contributions and improve the convergent behaviors of the operator product expansion, and we should bear in mind that the predictions are rather sensitive to the particular energy scales which obey the uniform/same constraint. The predicted vector hidden-charm tetraquark states can be confronted to the experimental data in the future.

hep-ph↗
arXiv2021

Analysis of the fully-heavy pentaquark states via the QCD sum rules

In the article, we investigate the diquark-diquark-antiquark type fully-heavy pentaquark states with the spin-parity $J^P={\frac{1}{2}}^-$ via the QCD sum rules, and obtain the masses $M_{cccc\bar{c}}=7.93\pm 0.15\,\rm{GeV}$ and $M_{bbbb\bar{b}}=23.91\pm0.15\,\rm{GeV}$. We can search for the fully-heavy pentaquark states in the $J/ψΩ_{ccc}$ and $ΥΩ_{bbb}$ invariant mass spectrum in the future.

hep-ph↗
arXiv2021

The $1D$, $2D$ $Ξ_{b}$ and $Λ_{b}$ baryons

Recently, scientists have made great progresses in experiments in searching for the excited states of $Ξ_{b}$ and $Λ_{b}$ baryons such as the $Λ_{b}(6072)$, $Λ_{b}(6146)$, $Λ_{b}(6152)$, $Ξ_{b}(6227)$, $Ξ_{b}(6100)$, $Ξ_{b}(6327)$ and $Ξ_{b}(6333)$. Stimulated by these progresses, we give a systematical analysis about the $1D$ and $2D$ states of $Ξ_{b}$ and $Λ_{b}$ baryons with the method of QCD sum rules. By constructing three types of interpolating currents, we calculate the masses and pole residues of these heavy baryons with different excitation modes $(L_ρ,L_λ)=(0,2)$, $(2,0)$ and $(1,1)$. As a result, we decode the inner structures of $Λ_{b}(6146)$, $Λ_{b}(6152)$, $Ξ_{b}(6327)$ and $Ξ_{b}(6333)$, and favor assigning these states as the $1D$ baryons with the quantum numbers $(L_ρ,L_λ)=(0,2)$ and $\frac{3}{2}^{+}$, $\frac{5}{2}^{+}$, $\frac{3}{2}^{+}$ and $\frac{5}{2}^{+}$, respectively. In addition, the predictions about the masses and pole residues of the other $1D$ and $2D$ states of $Ξ_{b}$ and $Λ_{b}$ baryons in this paper are helpful in studying the D-wave bottom baryons in experiments in the future.

hep-ph↗
arXiv2021

Tetraquark molecular states in the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ mass spectrum

In the present work, we construct the color-singlet-color-singlet type four-quark currents to investigate the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ tetraquark molecular states with the $J^{PC}=1^{--}$ and $1^{-+}$ via the QCD sum rules, and obtain satisfactory results. We can search for the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ tetraquark molecular states with the $J^{PC}=1^{--}$ and $1^{-+}$ at the BESIII and Belle II in the future.

hep-ph↗
arXiv2021

Analysis of the hidden-charm pentaquark molecular states with strangeness and without strangeness via the QCD sum rules

In this article, we investigate the $\bar{D}Σ_c$, $\bar{D}Ξ^\prime_c$, $\bar{D}Σ_c^*$, $\bar{D}Ξ_c^*$, $\bar{D}^{*}Σ_c$, $\bar{D}^{*}Ξ^\prime_c$, $\bar{D}^{*}Σ_c^*$ and $\bar{D}^{*}Ξ_c^*$ pentaquark molecular states with strangeness and without strangeness via the QCD sum rules at length, pay much attention to the light flavor $SU(3)$ breaking effects, and make predictions for new pentaquark molecular states besides assigning the $P_c(4312)$, $P_c(4380)$, $P_c(4440)$, $P_c(4457)$ and $P_{cs}(4459)$ self-consistently. We can search for those pentaquark molecular states in the decays of the $Λ_b^0$, $Ξ_b^0$ and $Ξ_b^-$ in the future. Furthermore, we discuss the higher dimensional vacuum condensates in details.

hep-ph↗
arXiv2021

Study of $Λ_c$$Λ_c$ dibaryon and $Λ_c$$\barΛ_c$ baryonium states via QCD sum rules

In this article, we construct the six-quark currents with the $J^P=0^+$, $0^-$, $1^+$ and $1^-$ to study the $Λ_c$$Λ_c$ dibaryon and $Λ_c$$\barΛ_c$ baryonium states via QCD sum rules. We consider the vacuum condensates up to dimension 16 and truncation of the order $\mathcal{O}(α_s^k )$ with $k\leq3$. The predicted masses are $5.11_{-0.12}^{+0.15}$GeV, $4.66_{-0.06}^{+0.10}$GeV, $4.99_{-0.09}^{+0.10}$GeV $4.68^{+0.08}_{-0.08}$GeV for the $J^P=0^+$, $0^-$, $1^+$ and $1^-$ states, respectively, which can be confronted to the experimental data in the future considering the high integrated luminosity at the center-of-mass energy about $4.8\,\rm{GeV}$ at the BESIII. We find the terms with $\frac{3}{2}< k \leq 3$ do play a tiny role, and we can ignore these terms safely in the QCD sum rules.

hep-ph↗
arXiv2021

Analysis of the $\overlineΞ_{cc}Ξ_{cc}$ hexaquark molecular state with the QCD sum rules

In this work, we construct the color-singlet-color-singlet type six-quark pseudoscalar current to investigate the $\overlineΞ_{cc}Ξ_{cc}$ hexaquark molecular state with the QCD sum rules, the predicted mass $M_X \sim 7.2\,\rm{GeV}$ supports assigning the $X(7200)$ to be the $\overlineΞ_{cc}Ξ_{cc}$ hexaquark molecular state with the quantum numbers $J^{PC}=0^{-+}$. The $X(7200)$ can decay through fusions of the $\bar{c}c$ and $\bar{q}q$ pairs, we can search for the $X(7200)$ and explore its properties in the $J/ψJ/ψ$, $χ_{c1}χ_{c1}$, $D^*\bar{D}^*$ and $D_1\bar{D}_1$ invariant mass spectrum in the future.

hep-ph↗
arXiv2021

The ground states and the first radially excited states of D-wave vector $ρ$ and $ϕ$ mesons

In this article, we firstly derive two QCD sum rules QCDSR I and QCDSR II which are respectively used to extract observable quantities of the ground states and the first radially excited states of D-wave vector $ρ$ and $ϕ$ mesons. In our calculations, we consider the contributions of vacuum condensates up to dimension-7 in the operator product expansion. The predicted masses for $1^{3}D_{1}$ $ρ$ meson and $2^{3}D_{1}$ $ϕ$ meson are consistent well with the experimental data of $ρ$($1700$) and $ϕ$($2170$). Besides, our analysis indicates that it is reliable to assign the recent reported $Y$($2040$) state as the $2^{3}D_{1}$ $ρ$ meson. Finally, we obtain the decay constants of these states with QCDSR I and QCDSR II. These predictions are helpful not only to reveal the structure of the newly observed $Y$($2040$) state but also to establish $ϕ$ meson and $ρ$ meson families.

hep-ph↗
arXiv2021

Analysis of the $Z_{cs}(3985)$ as the axialvector tetraquark state

In this paper, we choose the scalar and axialvector diquark operators in the color antitriplet as the fundamental building blocks to construct the four-quark currents and investigate the diquark-antidiquark type axialvector tetraquark states $c\bar{c}u\bar{s}$ in the framework of the QCD sum rules. The predicted tetraquark mass $M_Z=3.99\pm0.09\,\rm{GeV}$ is in excellent agreement with the experimental value $3985.2^{+2.1}_{-2.0}\pm1.7\,\rm{MeV}$ from the BESIII collaboration, which supports identifying the $Z_{cs}(3985)$ as the cousin of the $Z_c(3900)$ with the quantum numbers $J^{PC}=1^{+-}$. We take into account the light flavor $SU(3)$ mass-breaking effect to estimate the mass spectrum of the diquark-antidiquark type hidden-charm tetraquark states having the strangeness according to the previous works.

hep-ph↗
arXiv2021

Analysis of the hidden-charm tetraquark molecule mass spectrum with the QCD sum rules

In this article, we investigate the mass spectrum of the ground state hidden-charm tetraquark molecular states without strange, with strange and with hidden-strange via the QCD sum rules in a comprehensive way and revisit the assignments of the $X$, $Y$, $Z$ states in the scenario of tetraquark molecular states consistently based on the QCD sum rules.

hep-ph↗
arXiv2021

The hadronic coupling constants of the lowest hidden-charm pentaquark state with the QCD sum rules in rigorous quark-hadron duality

In this article, we illustrate how to calculate the hadronic coupling constants of the pentaquark states with the QCD sum rules based on rigorous quark-hadron quality, then study the hadronic coupling constants of the lowest diquark-diquark-antiquark type hidden-charm pentaquark state with the spin-parity $J^P={\frac{1}{2}}^-$ in details, and calculate the partial decay widths. The total width $Γ(P_c)=14.32\pm3.31\,\rm{MeV}$ is compatible with the experimental value $Γ_{P_c(4312)} = 9.8\pm2.7^{+ 3.7}_{- 4.5} \mbox{ MeV}$ from the LHCb collaboration, and favors assigning the $P_c(4312)$ to be the $[ud][uc]\bar{c}$ pentaquark state with the $J^P={\frac{1}{2}}^-$. The hadronic coupling constants have the relation $|G_{PD^-Σ_c^{++}}|= \sqrt{2}|G_{P\bar{D}^0Σ_c^+}|\gg |G_{P\bar{D}^0Λ_c^+}|$, and favor the hadronic dressing mechanism. The $P_c(4312)$ maybe have a diquark-diquark-antiquark type pentaquark core with the typical size of the $qqq$-type baryon states, the strong couplings to the meson-baryon pairs $\bar{D}Σ_c$ lead to some pentaquark molecule components, and the $P_c(4312)$ maybe spend a rather large time as the $\bar{D}Σ_c$ molecular state.

hep-ph↗