Related papers: Investigating different structures for the $X(3872…
From a study of the lineshape of the $X(3872)$, the LHCb collaboration measures a sizeable negative effective range. This cannot be reconciled with a shallow $D\bar{D}^*$ bound state hypothesis. Based on Weinberg's compositeness criterion,…
We present preliminary quenched results on a new operator for the investigation of string-breaking within SU(2)-colour QCD. The ground-state of a spatially-separated static-light meson-antimeson pair is a combination of a state with two…
We revisit the hidden-charm pentaquark states $P_c(4380)$ and $P_c(4450)$ using the method of QCD sum rules by requiring the pole contribution to be larger than or around 30\% to better insure the one-pole parametrization to be valid. We…
In this work, we introduce an explicit P-wave to construct the diquarks $[qc]_{\widehat{V}}$, then construct the local four-quark currents to explore the hidden-charm tetraquark states with the $J^{PC}=0^{++}$, $1^{+-}$ and $2^{++}$ in the…
The talk discusses preliminary results of an updated analysis of the strange quark mass from the scalar current QCD sum rules [1]. In particular the role of the scalar form factor which is a main ingredient in the analysis is especially…
We study $\bar{Q}Q\bar{q}q$ and $\bar{Q}qQ\bar{q}$ states as mixed states in QCD sum rules. By calculating the two-point correlation functions of pure states of their corresponding currents, we review the mass and coupling constant…
Recent results on the hadron spectroscopy from lattice QCD are reviewed with emphasis on the meson sector and in particular on quarkonium-like $XYZ$ states. I report on the first rigorous treatment of the near-threshold states $X(3872)$ and…
We report on some ideas concerning the nature of the X(3872) resonance and the need for approximately equal charged and neutral components of $D \bar{D}^* +cc$. Then we discuss how some hidden charm states are obtained from the interaction…
We summarize some recent results on the structure of QCD at very high baryon density.
To illustrate the campaign to understand heavy quarkonium systems, I focus on a puzzling new state, $X(3872) \to \pi^+\pi^- J/\psi$. Studying the influence of open-charm channels on charmonium properties leads us to propose a new charmonium…
In this article, we construct the diquark-diquark-antiquark type interpolating currents, and study the masses and pole residues of the $J^P={\frac{3}{2}}^-$ and ${\frac{5}{2}}^+$ hidden-charmed pentaquark states in details with the QCD sum…
We investigate the newly observed $X(4500)$ and $X(4700)$ based on the diquark-antidiquark configuration within the framework of QCD sum rules. Both of them may be interpreted as the $D$-wave $cs\bar{c}\bar{s}$ tetraquark states of $J^P =…
The SU(3)_flavor constituent quark model has been quite successful to explain the properties as well as the observed spectrum of mesons with pseudoscalar and vector quantum numbers. Many radial and orbital excitations of quark-antiquark…
Motivated by the analogous properties of the $Z_c(3900/3885)$ and $Z_{cs}(3985/4000)$, we tentatively assign the $Z_c(4020/4025)$ as the $A\bar{A}$-type hidden-charm tetraquark state with the $J^{PC}=1^{+-}$, where the $A$ denotes the…
We investigated the four-quark systems with quark structures of $cs\bar{c}\bar{s}$, $cq\bar{c}\bar{s}$, $bs\bar{b}\bar{s}$, and $bq\bar{b}\bar{s}$ in the framework of the non-relativistic quark model, motivated by the recent observation of…
Assuming four-quark structure for the $X$ resonances in low-lying region, we calculate their masses using the color-spin interaction. In specific, the hyperfine masses of the color-spin interaction are calculated for the possible states in…
The ${q}\bar{q}$ spectrum is studied within a chiral constituent quark model. It provides with a good fit of the available experimental data from light (vector and pseudoscalar) to heavy mesons including some recent results on charmonium.…
Despite the apparent simplicity of meson spectroscopy there are some states which cannot be accommodated in the usual $q\bar q$ structure. Among them there are either exotic states as the X(1600), or the recently measured charmed states…
In this article, we take the tensor currents $\bar{Q}(x)\sigma_{\mu\nu}Q(x)$ to interpolate the $P$-wave spin-singlet heavy quarkonium states $h_Q$, and study the masses and decay constants with the Borel sum rules and moments sum rules.…
The properties of open strange meson $K_1^\pm$ in nuclear matter are estimated in the QCD sum rule approach. We obtain a relation between the in-medium mass and width of $K_1^-$ ($K_1^+$) in nuclear matter, and show that the upper limit of…