arXiv subjects
Publications and source records attributed to Zhi-Gang Wang.
In this article, we study the pseudoscalar bound state $η_c'f_0(980)$ (irrespective of the hadro-charmonium and the molecular state) with the QCD sum rules. Considering the SU(3) symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states $η_c'σ(400-1200)$, $η_b'''f_0(980)$ and $η_b'''σ(400-1200)$, and make reasonable predictions for their masses.
In this article, we study the mass spectrum of the scalar hidden charm and hidden bottom tetraquark states which consist of the axial-axial type and the vector-vector type diquark pairs with the QCD sum rules.
In this article, we use the light-cone QCD sum rules to relate the $Λ_b$ baryon light-cone distribution amplitudes to the Isgur-Wise function $ξ(ω)$ of the $Λ_b \to Λ_c$ transition, and obtain a simple relation. The numerical value of the Isgur-Wise function $ξ(ω)$ is consistent with the prediction of the QCD sum rules.
In this article, we take the vector charmonium-like state Y(4660) as a $ψ'f_0(980)$ bound state (irrespective of the hadro-charmonium and the molecular state) tentatively, study its mass using the QCD sum rules, the numerical value $M_Y=4.71\pm0.26 \rm{GeV}$ is consistent with the experimental data. Considering the SU(3) symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states $ψ'σ(400-1200)$, $Υ'"f_0(980)$ and $Υ"'σ(400-1200)$ with the QCD sum rules, and make reasonable predictions for their masses.
In this article, we assume that there exist scalar ${D}^\ast {\bar {D}}^\ast$, ${D}_s^\ast {\bar {D}}_s^\ast$, ${B}^\ast {\bar {B}}^\ast$ and ${B}_s^\ast {\bar {B}}_s^\ast$ molecular states, and study their masses using the QCD sum rules. The numerical results indicate that the masses are about $(250-500) \rm{MeV}$ above the corresponding ${D}^\ast -{\bar {D}}^\ast$, ${D}_s^\ast -{\bar {D}}_s^\ast$, ${B}^\ast -{\bar {B}}^\ast$ and ${B}_s^\ast -{\bar {B}}_s^\ast$ thresholds, the Y(4140) is unlikely a scalar ${D}_s^\ast {\bar {D}}_s^\ast$ molecular state. The scalar $D^\ast {\bar D}^\ast$, $D_s^\ast {\bar D}_s^\ast$, $B^\ast {\bar B}^\ast$ and $B_s^\ast {\bar B}_s^\ast$ molecular states maybe not exist, while the scalar ${D'}^\ast {\bar {D'}}^\ast$, ${D'}_s^\ast {\bar {D'}}_s^\ast$, ${B'}^\ast {\bar {B'}}^\ast$ and ${B'}_s^\ast {\bar {B'}}_s^\ast$ molecular states maybe exist.
In this article, we assume that there exists a scalar $D_s^\ast {\bar D}_s^\ast$ molecular state in the $J/ψϕ$ invariant mass distribution, and study its mass using the QCD sum rules. The predictions depend heavily on the two criteria (pole dominance and convergence of the operator product expansion) of the QCD sum rules. The value of the mass is about $M_{D_s^\ast {\bar D}_s^\ast}=(4.43\pm0.16) \rm{GeV}$, which is inconsistent with the experimental data. The $D_s^\ast {\bar D}_s^\ast$ is probably a virtual state and not related to the meson Y(4140). Other possibility, such as a hybrid charmonium is not excluded.
In this article, we perform a systematic study of the mass spectrum of the vector hidden charmed and bottomed tetraquark states using the QCD sum rules.
In this article, we study the mass spectrum of the scalar hidden charm and bottom tetraquark states with the QCD sum rules. The numerical results are compared with the corresponding ones from a relativistic quark model based on a quasipotential approach in QCD. The relevant values from the constituent diquark model based on the constituent diquark masses and the spin-spin interactions are also discussed.
In this article, we assume that there exists a scalar hidden charm tetraquark state in the $π^+ χ_{c1}$ invariant mass distribution, and study its mass using the QCD sum rules. The numerical result $M_{Z}=(4.36\pm0.18) \rm{GeV}$ is consistent with the mass of the Z(4250). The Z(4250) may be a tetraquark state, other possibilities, such as a hadro-charmonium resonance and a $D_1^+\bar{D}^0+ D^+\bar{D}_1^0$ molecular state are not excluded.
In this article, we calculate the strong coupling constant $g$ among the decuplet baryons, the octet baryons and the pseudoscalar mesons in the heavy baryon chiral perturbation theory with the light-cone QCD sum rules, and study the strong decays $Σ^* \to Λπ,Σπ$. The numerical value of the strong coupling constant $g$ is consistent with our previous calculation, the central values lead to small SU(3) breaking effects, less than 6%; and no definitive conclusion can be drawn due to the large uncertainties.
In this article, we assume that the $(0^+,1^+)$ strange-bottom mesons are the conventional $b\bar{s}$ mesons, and calculate the electromagnetic coupling constants $d$, $g_1$, $g_2$ and $g_3$ using the light-cone QCD sum rules. Then we study the radiative decays $B_{s0}\to B_s^* γ$, $B_{s1}\to B_s γ$, $B_{s1}\to B_s^* γ$ and $B_{s1}\to B_{s0} γ$, and observe that the widths are rather narrow. We can search for the $(0^+,1^+)$ strange-bottom mesons in the invariant $B_s π^0$ and $B^*_s π^0$ mass distributions in the strong decays or in the invariant $B_s^*γ$ and $B_sγ$ mass distributions in the radiative decays.
In this article, we calculate the contribution from the nonfactorizable soft hadronic matrix element to the decay $B^0\to χ_{c1} π^0$ with the light-cone QCD sum rules. The numerical results show that its contribution is rather large and should not be neglected. The total amplitudes lead to a branching fraction which is in agreement with the experimental data marginally.
In this article, we calculate the masses and the pole residues of the ${1/2}^+$ heavy baryons $Ω_c^0(css)$ and $Ω_b^-(bss)$ with the QCD sum rules. The numerical values $M_{Ω_c^0}=(2.72\pm0.18) \rm{GeV}$ (or $M_{Ω_c^0}=(2.71\pm0.18) \rm{GeV}$) and $M_{Ω_b^-}=(6.13\pm0.12) \rm{GeV}$ (or $M_{Ω_b^-}=(6.18\pm0.13) \rm{GeV}$) are in good agreement with the experimental data.
In this article, we take the point of view that the light scalar meson $a_0(980)$ is a conventional $q\bar{q}$ state, and calculate the coupling constants $g_{a_0ηπ^0}$ and $g_{a_0 η'π^0}$ with the light-cone QCD sum rules. The central value of the coupling constant $g_{a_0ηπ^0}$ is consistent with the one extracted from the radiative decay $ϕ(1020)\to a_0(980)γ\to ηπ^0 γ$. The central value and lower bound of the decay width $Γ_{a_{0}\to ηπ^0}=127^{+84}_{-48} \rm{MeV} $ are compatible with the experimental data of the total decay width $Γ_{a_0(980)}=(50-100) \rm{MeV}$ from the Particle Data Group with very model dependent estimation (the decay width can be much larger), while the upper bound is too large. We give possible explanation for the discrepancy between the theoretical calculation and experimental data.
In this article, we assume that there exist hidden charmed tetraquark states with the spin-parity $J^P=1^-$, and calculate their masses with the QCD sum rules. The numerical result indicates that the masses of the vector hidden charmed tetraquark states are about $M_{Z}=(5.12\pm0.15) \rm{GeV}$ or $M_{Z}=(5.16\pm0.16) \rm{GeV}$, which are inconsistent with the experimental data on the $π^+ χ_{c1}$ invariant mass distribution. The hidden charmed mesons $Z_1$, $Z_2$ or $Z$ may be scalar hidden charmed tetraquark states, hadro-charmonium resonances or molecular states.
In this article, we study the final-state rescattering effects in the decay $B^0 \to η_cK^*$, the numerical results indicate the corrections are comparable with the contribution from the naive factorizable amplitude, and the total amplitudes can accommodate the experimental data.
In this article, we calculate the masses and decay constants of the $P$-wave strange-bottomed mesons $B_{s0}$ and $B_{s1}$ with the QCD sum rules, and observe that the central values of the masses of the $B_{s0}$ and $B_{s1}$ are smaller than the corresponding $BK$ and $B^*K$ thresholds respectively, the strong decays $B_{s0}\to BK$ and $B_{s1}\to B^*K$ are kinematically forbidden. They can decay through the isospin violation precesses $B_{s0}\to B_sη\to B_sπ^0$ and $B_{s1}\to B_s^*η\to B_s^*π^0$. The bottomed mesons $B_{s0}$ and $B_{s1}$, just like their charmed cousins $D_{s0}(2317)$ and $D_{s1}(2460)$, maybe very narrow.
In this article, we calculate the $B\to a_1(1260)$ form-factors $V_1(q^2)$, $V_2(q^2)$, $V_3(q^2)$ and $A(q^2)$ with the $B$-meson light-cone QCD sum rules. Those form-factors are basic parameters in studying the exclusive non-leptonic two-body decays $B\to AP$ and semi-leptonic decays $B\to A l ν_l$, $B\to A \bar{l}l$. Our numerical results are consistent with the values from the (light-cone) QCD sum rules. The main uncertainty comes from the parameter $ω_0$ (or $λ_B$), which determines the shapes of the two-particle and three-particle light-cone distribution amplitudes of the $B$ meson, it is of great importance to refine this parameter.