Analysis of the strong vertices of ΣcND∗\Sigma_cND^{*} and ΣbNB∗\Sigma_bNB^{*} in QCD sum rules

The strong coupling constant is an important parameter which can help us to understand the strong decay behaviors of baryons. In our previous work, we have analyzed strong vertices $\Sigma_{c}^{*}ND$, $\Sigma_{b}^{*}NB$, $\Sigma_{c}ND$, $\Sigma_{b}NB$ in QCD sum rules. Following these work, we further analyze the strong vertices $\Sigma_{c}ND^{*}$ and $\Sigma_{b}NB^{*}$ using the three-point QCD sum rules under Dirac structures $q\!\!\!/p\!\!\!/\gamma_{\alpha}$ and $q\!\!\!/p\!\!\!/p_{\alpha}$. In this work, we first calculate strong form factors considering contributions of the perturbative part and the condensate terms $\langle\overline{q}q\rangle$, $\langle\frac{\alpha_{s}}{\pi}GG\rangle$ and $\langle\overline{q}g_{s}\sigma Gq\rangle$. Then, these form factors are used to fit into analytical functions. According to these functions, we finally determine the values of the strong coupling constants for these two vertices $\Sigma_{c}ND^{*}$ and $\Sigma_{b}NB^{*}$.Comment: arXiv admin note: text overlap with arXiv:1705.0322

Zc(3900)Z_c(3900) as a DDˉ∗D\bar{D}^* molecule from the pole counting rule

A comprehensive study on the nature of the $Z_c(3900)$ resonant structure is carried out in this work. By constructing the pertinent effective Lagrangians and considering the important final-state-interaction effects, we first give a unified description to all the relevant experimental data available, including the $J/\psi\pi$ and $\pi\pi$ invariant mass distributions from the $e^+e^-\to J/\psi\pi\pi$ process, the $h_c\pi$ distribution from $e^+e^-\to h_c\pi\pi$ and also the $D\bar D^{*}$ spectrum in the $e^+e^-\to D\bar D^{*}\pi$ process. After fitting the unknown parameters to the previous data, we search the pole in the complex energy plane and find only one pole in the nearby energy region in different Riemann sheets. Therefore we conclude that $Z_c(3900)$ is of $D\bar D^*$ molecular nature, according to the pole counting rule method~[Nucl.~Phys.~A543, 632 (1992); Phys.~Rev.~D 35,~1633 (1987)]. We emphasize that the conclusion based upon the pole counting method is not trivial, since both the $D\bar D^{*}$ contact interactions and the explicit $Z_c$ exchanges are introduced in our analyses and they lead to the same conclusion.Comment: 21 pages, 9 figures. To match the published version in PRD. Additional discussion on the spectral density function is include

Tuberostemoamide hemihydrate

In the crystal structure of the title compound {systematic name: (1′S,2R,2′R,3′S,6′R)-3′-ethyl-4-methyl-5H-5′-oxa-10′-aza­spiro­[furan-2,4′-tricyclo­[8.3.0.02,6]trideca­ne]-5,11′-dione hemihydrate}, C17H23NO4·0.5H2O, the asymmetric unit contains two mol­ecules of tuberostemoamide with similar conformations and one water mol­ecule. The tuberostemoamide mol­ecule is composed of one seven-membered ring (A) and three five-membered rings (B, C and D). Ring A exists in a chair conformation, both rings B and C exist in envelope conformations, and ring D is almost planar with a mean deviation of 0.0143 (4) Å in one molecule and 0.0095 (3) Å in the other.. The dihedral angles between the planes of rings C and D are 75.1 (3)° in one mol­ecule and 74.5 (3)° for the other. The solvent water mol­ecule links the tuberostemoamide mol­ecules through O—H⋯O(ketone) hydrogen bonds. Weak C—H⋯O inter­actions are also present, involving both the water mol­ecule and a heterocyclic ether O-atom acceptor