Related papers: Sigma meson in pole-dominated QCD sum rules
We study the light scalar mesons in the QCD sum rule. We construct both the diquark-antidiquark currents $(qq)(\bar q \bar q)$ and the meson-meson currents $(\bar qq)(\bar qq)$. We find that there are five independent currents for both…
In this article, we construct the color-singlet-color-singlet type currents and the color-singlet-color-singlet-color-singlet type currents to study the scalar $D^*\bar{D}^*$, $D^*D^*$ tetraquark molecular states and the vector…
We investigate f_0-sigma mixing in the framework of light cone QCD sum rules and by employing the experimental results about the decay widths and the masses of these scalar mesons we estimate the scalar mixing angle by using sigma meson…
In this article, we take the pseudoscalar, scalar, axialvector, vector, tensor (anti)diquark operators as the basic constituents, and construct the scalar, axialvector and tensor tetraquark currents to study the mass spectrum of the ground…
In the SU(3) symmetry limit, the ratio $R\equiv\frac{{\cal B}(D^+\to f_0l^+\nu)+ {\cal B}(D^+\to \sigma l^+\nu)}{{\cal B}(D^+\to a_0^0l^+\nu)}$ is equal to 1 if the scalar mesons are $\bar qq$ states, while it is 3 if these mesons are…
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.…
We test the validity of the QCD sum rules applied to the meson $Z^+(4430)$, by considering a diquark-antidiquark type of current with $J^{P}=0^{-}$ and with $J^{P}=1^{-}$. We find that, with the studied currents, it is possible to find an…
The light scalar meson spectrum is studied using the improved ladder QCD with the UA(1) breaking Kobayashi-Maskawa-'t Hooft interaction by solving the Schwinger-Dyson and Bethe-Salpeter equations. The dynamically generated…
In order to investigate the possibility of the recently observed $X(5568)$ being a $0^{+}$ tetraquark state, we make an improvement to the study of the related various configuration states in the framework of the QCD sum rules.…
We use QCD sum rules to study the possible existence of $QQ-\bar{u}\bar{d}$ mesons, assumed to be a state with $J^{P}=1^{+}$. For definiteness, we work with a current with an axial heavy diquark and a scalar light antidiquark, at leading…
We summarize the different features of the scalar mesons from QCD spectral sum rule analyses of the two- and three-point functions. The results do not favour the u-bar u + d-bar d interpretation of the broad and low mass sigma (0.6), and…
Parameters of the heavy four-quark scalar meson $T_{\mathrm{bc\overline{b} \overline{c}}}$ with content $bc \overline{b}\overline{c}$ are calculated by means of the sum rule method. This structure is considered as a diquark-antidiquark…
We perform a QCD sum rule analysis for the light scalar meson $\sigma$ ($f_0(600)$) with a tetraquark current related to the instanton picture for QCD vacuum. We demonstrate that instanton current, including equal weights of scalar and…
By assuming SU(6)_cs symmetry for pentaquark decays one finds a selection rule, which strongly reduces the number of states able to decay into a baryon and a meson final state and allows an intriguing identification for the Theta^+ particle…
We study the lowest-lying scalar mesons in the QCD sum rule by considering them as tetraquark states. We find that there are five independent currents for each state with a certain flavor structure. By forming linear combinations, we find…
In this article, we study the axialvector-diquark-axialvector-antidiquark type scalar, axialvector, tensor and vector $ss\bar{s}\bar{s}$ tetraquark states with the QCD sum rules. The predicted mass $m_{X}=2.08\pm0.12\,\rm{GeV}$ for the…
QCD sum-rule studies have been useful to understand and get an insight on the structure of exotic states, such as tetraquark systems. Moreover, the majority of these studies are performed only at leading-order (LO) within the light…
Properties of doubly charged scalar tetraquarks $bb\overline{c}\overline{c}$ are investigated in the framework of the QCD sum rule method. We model them as diquark-antidiquark states $X_{\mathrm{1}}$ and $X_{\mathrm{2}}$ built of…
The mass and width of the tensor tetraquark $T=bb\overline{c}\overline{c}$ with spin-parity $J^{\mathrm{P}}=2^{+}$ are calculated in the context of the QCD sum rule method. The tetraquark $T$ is modeled as a diquark-antidiquark state built…
In this work, we take all the color-antitriplet diquarks, such as the scalar, pseudoscalar, vector, axialvector and tensor diquarks, as the basic constituents to construct the local pseudoscalar four-quark currents without importing the…