Reanalysis of the Y(3940)Y(3940), Y(4140)Y(4140), Zc(4020)Z_c(4020), Zc(4025)Z_c(4025) and Zb(10650)Z_b(10650) as molecular states with QCD sum rules

In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the $J^{PC}=0^{++}$, $1^{+-}$, $2^{++}$ $D^*\bar{D}^*$, $D_s^*\bar{D}_s^*$, $B^*\bar{B}^*$, $B_s^*\bar{B}_s^*$ molecular states with the QCD sum rules. In calculations, we use the formula $\mu=\sqrt{M^2_{X/Y/Z}-(2{\mathbb{M}}_Q)^2}$ to determine the energy scales of the QCD spectral densities. The numerical results favor assigning the $Z_c(4020)$ and $Z_c(4025)$ as the $J^{PC}=0^{++}$, $1^{+-}$ or $2^{++}$ $D^*\bar{D}^*$ molecular states, the $Y(4140)$ as the $J^{PC}=0^{++}$ $D^*_s{D}_s^*$ molecular state, the $Z_b(10650)$ as the $J^{PC}=1^{+-}$ $B^*\bar{B}^*$ molecular state, and disfavor assigning the $Y(3940)$ as the ($J^{PC}=0^{++}$) molecular state. The present predictions can be confronted to the experimental data in the futures.Comment: 24 pages, 26 figures. arXiv admin note: substantial text overlap with arXiv:1312.1537, arXiv:1312.7489, arXiv:1311.1046, arXiv:1312.265

Analysis of the Λc(2860)\Lambda_c(2860), Λc(2880)\Lambda_c(2880), Ξc(3055)\Xi_c(3055) and Ξc(3080)\Xi_c(3080) as D-wave baryon states with QCD sum rules

In this article, we tentatively assign the $\Lambda_c(2860)$, $\Lambda_c(2880)$, $\Xi_c(3055)$ and $\Xi_c(3080)$ to be the D-wave baryon states with the spin-parity $J^P={\frac{3}{2}}^+$, ${\frac{5}{2}}^+$, ${\frac{3}{2}}^+$ and ${\frac{5}{2}}^+$, respectively, and study their masses and pole residues with the QCD sum rules in a systematic way by constructing three-types interpolating currents with the quantum numbers $(L_\rho,L_\lambda)=(0,2)$, $(2,0)$ and $(1,1)$, respectively. The present predictions favor assigning the $\Lambda_c(2860)$, $\Lambda_c(2880)$, $\Xi_c(3055)$ and $\Xi_c(3080)$ to be the D-wave baryon states with the quantum numbers $(L_\rho,L_\lambda)=(0,2)$ and $J^P={\frac{3}{2}}^+$, ${\frac{5}{2}}^+$, ${\frac{3}{2}}^+$ and ${\frac{5}{2}}^+$, respectively. While the predictions for the masses of the $(L_\rho,L_\lambda)=(2,0)$ and $(1,1)$ D-wave $\Lambda_c$ and $\Xi_c$ states can be confronted to the experimental data in the future.Comment: 26 pages, 25 figure

Analysis of the QQQˉQˉQQ\bar{Q}\bar{Q} tetraquark states with QCD sum rules

In this article, we study the $J^{PC}=0^{++}$ and $2^{++}$ $QQ\bar{Q}\bar{Q}$ tetraquark states with the QCD sum rules, and obtain the predictions $M_{X(cc\bar{c}\bar{c},0^{++})} =5.99\pm0.08\,\rm{GeV}$, $M_{X(cc\bar{c}\bar{c},2^{++})} =6.09\pm0.08\,\rm{GeV}$, $M_{X(bb\bar{b}\bar{b},0^{++})} =18.84\pm0.09\,\rm{GeV}$ and $M_{X(bb\bar{b}\bar{b},2^{++})}=18.85\pm0.09\,\rm{GeV}$, which can be confronted to the experimental data in the future. Furthermore, we illustrate that the diquark-antidiquark type tetraquark state can be taken as a special superposition of a series of meson-meson pairs and embodies the net effects.Comment: 18 pages, 17 figure