arXiv subjects
Publications and source records attributed to Zhi-Gang Wang.
In this article, we calculate the strong coupling constant $g_{ΔNπ}$ and study the strong decay $Δ^{++} \to pπ$ with the light-cone QCD sum rules. The numerical value of the strong coupling constant $g_{ΔNπ}$ is consistent with the experimental data. The small discrepancy maybe due to failure to take into account the perturbative $\mathcal {O}(α_s)$ corrections.
In this article, we calculate the electromagnetic form-factor of the $π$ meson with the light-cone QCD sum rules. The numerical value $F_π^{p}(0) =0.999\pm 0.001$ is in excellent agreement with the experimental data (extrapolated to the limit of zero momentum transfer, or the normalization condition $F_π(0)=1$). For large momentum transfers, the values from the two sum rules are all comparable with the experimental data and theoretical estimations.
In this article, we take the point of view that the $D_s(2700)$ be a tetraquark state, which consists of a scalar diquark and a vector antidiquark, and calculate its mass with the QCD sum rules. The numerical result indicates that the mass of the vector charmed tetraquark state is about $M_V=(3.75\pm0.18)\rm{GeV}$ or $M_V=(3.71\pm0.15)\rm{GeV}$ from different sum rules, which is about $1\rm{GeV}$ larger than the experimental data. Such tetraquark component should be very small in the $D_s(2700)$.
In this article, we analyze the vertex $D^*D^*ρ$ with the light-cone QCD sum rules. The strong coupling constant $g_{D^*D^*ρ}$ is an important parameter in evaluating the charmonium absorption cross sections in searching for the quark-gluon plasmas. Our numerical value for the $g_{D^*D^*ρ}$ is consistent with the prediction of the effective SU(4) symmetry and vector meson dominance theory.
In this article, we calculate the masses and residues of the heavy baryons $Ω_c^*(css)$ and $Ω_b^*(bss)$ with spin-parity ${3/2}^+$ with the QCD sum rules. The numerical values are compatible with experimental data and other theoretical estimations.
In this article, we study the contribution from the final-state interactions to the strong coupling constant $g_{D^* D π}$. We take an assumption that the momentum transfers in the strong decay $D^{*+} \to D^0 π^+$ be large to validate the operator product expansion in the light-cone QCD sum rules. At large momentum transfers, the final-state interactions play an important role, and we should take them into account.
In this article, we study the vertices $D^*D^*P$, $D^*DV$ and DDV with the light-cone QCD sum rules. The strong coupling constants g_{D^*D^*P}, g_{D^*DP}, f_{D^*DV}, f_{D^*D^*V}, g_{DDV} and g_{D^*D^*V} play an important role in understanding the final-state interactions in the hadronic B decays. They relate to the basic parameters g, $λ$ and $β$ in the heavy quark effective Lagrangian respectively. Our numerical values of the g, $β$ and $λ$ are much smaller than most of the existing estimations. If the predictions from the light-cone QCD sum rules are robust, the final-state interaction effects maybe overestimated in the hadronic B decays.
In this article, we study the vertices $DDV$ and $D^*DV$ with the light-cone QCD sum rules. The strong coupling constants $g_{DDV}$ and $f_{D^*DV}$ play an important role in understanding the final-state re-scattering effects in the hadronic B decays. They are related to the basic parameters $β$ and $λ$ respectively in the heavy quark effective Lagrangian, our numerical values are smaller than the existing estimations.
In this article, we calculate the strong coupling constants of the $ρNN$, $ρΣΣ$ and $ρΞΞ$ in the framework of the light-cone QCD sum rules approach. The strong coupling constants of the meson-baryon-baryon are the fundamental parameters in the one-boson exchange model which describes the baryon-baryon interactions successfully. The numerical values are in agreement with the existing calculations in part. The electric and magnetic $F/(F+D)$ ratios deviate from the prediction of the vector meson dominance theory, the SU(3) symmetry breaking effects are very large.
In this article, we calculate the scalar form-factors $f_{ππ}(Q^2)$ and $f_{KK}(Q^2)$ in the framework of the light-cone QCD sum rules approach. The numerical value of the $f_{ππ}(Q^2)$ changes quickly with variation of $Q^2$ near zero momentum transfer, while the $f_{KK}(Q^2)$ has rather good behavior at small momentum transfer. The value $f_{KK}(0) =2.21^{+0.35}_{-0.19} GeV$ is compatible with the result from the leading order chiral perturbation theory. At large momentum transfer with $Q^2> 6GeV^2$, the form-factor $f_{ππ}(Q^2)$ takes up the asymptotic behavior $\frac{1}{Q^2}$ approximately, while the $f_{KK}(Q^2)$ decreases more quickly than $\frac{1}{Q^2}$.
In this article, we take the point of view that the charmed mesons $D_{s0}(2317)$ and $D_{s1}(2460)$ with the spin-parity $0^+$ and $1^+$ respectively are the conventional $c\bar{s}$ states, and calculate the strong coupling constants $G_S$(for $ $) and $G_A$(for $ $) in the framework of the light-cone QCD sum rules approach. The strong coupling constants $G_S$ and $G_A$ are related to the basic parameter $\hatμ$ in the heavy quark effective Lagrangian, the numerical value is larger than the existing estimation. With the assumption of the vector meson dominance of the intermediate $ϕ(1020)$, we study the radiative decays $D_{s0}\to D_s^* γ$ and $D_{s1}\to D_s γ$.
In this article, we take the point of view that Y(2175) be a tetraquark state which consists of color octet constituents, and calculate its mass and decay constant within the framework of the QCD sum rule approach. We release standard criterion in the QCD sum rules approach and take more phenomenological analysis, the value of the mass of Y(2175) is consistent with experimental data; there may be some tetraquark components in the state Y(2175). If we retain standard criterion, larger mass than experimental data can be obtained, the current $J_μ(x)$ can interpolate a tetraquark state with larger mass, or Y(2175) has some components with larger mass. The dominating contribution comes from the perturbative term, which is in contrast to the sum rules with interpolating currents constructed from diquark pairs. The tetraquark states may consist of color octet constituents rather than diquark pairs.
Vector hybrid states with light quarks $u,d,s$ are investigated via QCD sum rules. The results show that the masses of the $q{\bar q}g$ $(q=u,d)$, $q{\bar s}g$, and $s{\bar s}g$ states with $J^{PC}=1^{--}$ are about 2.3-2.4, 2.3-2.5, and 2.5-2.6 GeV, respectively. It suggests that the recently discovered Y(2175) could not be a pure $s{\bar s}g$ vector hybrid state.
In this article, we take the point of view that the X(1835) be a baryonium state and calculate its mass within the framework of the QCD sum rules approach. The numerical value of the mass of the X(1835) is consistent with the experimental data. There may be some baryonium component in the X(1835) state.
In this letter, we take the point of view that the X(1576) be tetraquark state which consists of a scalar-diquark and an anti-scalar-diquark in relative $P$-wave, and calculate its mass in the framework of the QCD sum rules approach. The numerical value of the mass $m_X=(1.66\pm 0.14) GeV$ is consistent with the experimental data, there may be some tetraquark component in the vector meson X(1576).
In this article, we take the point of view that the charmed scalar meson $D_{s0}(2317)$ be a tetraquark state and devote to calculate its mass within the framework of the QCD sum rules approach in the heavy quark limit. The numerical values for the mass of the $D_{s0}(2317)$ are consistent with the experimental data, there must be some tetraquark component in the scalar meson $D_{s0}(2317)$. Detailed discussions about the threshold parameter and Borel parameter for the multiquark states are also presented.
In this article, we calculate the axial and the induced pseudoscalar form-factors $G_A(t=-Q^2)$ and $G_P(t=-Q^2)$ of the nucleons in the framework of the light-cone QCD sum-rules approach up to twist-6 three valence quark light-cone distribution amplitudes, and observe that the form-factors $G_A(t=-Q^2)$ and $G_P(t=-Q^2)$ at intermediate and large momentum transfers with $Q^2> 2 GeV^2$ have significant contributions from the end-point (soft) terms. The numerical values for the axial form-factor $G_A(t=-Q^2)$ are compatible with the experimental data and theoretical calculations, for example, the chiral quark models and lattice QCD. The numerical values for the induced pseudoscalar form-factor $G_P(t=-Q^2)$ are compatible with the calculation from the Bethe-Salpeter equation.
In this article, we calculate the scalar form-factor of the proton in the framework of the light-cone QCD sum rules approach with the three valence quark light-cone distribution amplitudes up to twist-6, and observe the scalar form-factor $σ(t=-Q^2)$ at intermediate and large momentum transfers $Q^2> 2GeV^2$ has significant contributions from the end-point (or soft) terms. The numerical values for the $σ(t=-Q^2)$ are compatible with the calculations from the chiral quark model and lattice QCD at the region $Q^2>2GeV^2$.