Related papers: Tetraquark-adequate QCD sum rules for quark-exchan…
A proper way of subtracting the continuum contributions in light-cone QCD sum rules (LCQSR) is demonstrated. Specifically, we calculate the continuum corresponding to a typical OPE appearing in LCQSR by properly combining the double…
In this work we investigate the existence of bound states for doubly heavy tetraquark systems $ \bar{Q}\bar{Q}'qq' $ in a full lattice-QCD computation, where heavy bottom quarks are treated in the framework of non-relativistic QCD. We focus…
We use QCD sum rules to determine the difference between moments of the non-singlet structure functions. This combination decouples from the singular behaviour of the structure functions near x=1 as calculated in the quark-gluon basis and…
The quarks and gluons are confined objects, they cannot be put on the mass-shell, it is questionable to apply the Landau equation to study the Feynman diagrams in the QCD sum rules. Furthermore, we carry out the operator product expansion…
In this study, the spectroscopic parameters of the exotic molecular states composed of mesons containing two heavy quarks (scalar-axial and pseudoscalar-axial meson combinations) are investigated within QCD sum rules. Our findings reveal…
The strong decays of the pseudoscalar and scalar double-charmed tetraquarks $ T_{cc;\overline{u}\overline{d}}^{+}$ and $\widetilde{T}_{cc;\overline{u} \overline{d}}^{+}$ are investigated in the framework of the QCD sum rule method. The mass…
We introduce a relative P-wave to construct the vector doubly-charm diquark $(\widetilde{V})$, therefore, the scalar and tensor four-quark currents to investigate the decay widths of the fully-charm tetraquark states with the…
In this article, we assume that the two quarks have unequal masses and calculate the next-to-leading order contributions to the spectral densities of the mesonic two-point correlation functions of the vector, axialvector, scalar and…
In this article, we construct the diquark-antidiquark type current operators to study the axialvector $B_c$-like tetraquark states with the QCD sum rules. In calculations, we take the energy scale formula as a powerful constraint to choose…
In the present work, we adopt the scalar, pseudoscalar, vector, axialvector and tensor (anti)diquark operators as the elementary building blocks to construct vector and tensor local four-quark currents without introducing explicit P-waves,…
The mass spectra of doubly heavy baryons are systematically calculated in the framework of QCD sum rules. With a tentative heavy-diquark--light-quark configuration, the interpolating currents representing the doubly heavy baryons are…
We discuss two types of contributions to hadronic form factors in QCD: hard gluon exchange and soft wave function overlap. Within the QCD sum rule approach, the hard contribution has strong numeric suppression by factor (\alpha_s/\pi) ~ 0.1…
The masses of baryons containing two heavy quarks and their couplings to the corresponding quark currents are evaluated in the framework of NRQCD sum rules. The coulomb-like corrections in the system of doubly heavy diquark are taken into…
A recently proposed scheme is used to saturate the spectral side of the QCD sum rules derived from the thermal, two-point correlation functions of the vector and the axial-vector currents. At low temperature, it constructs the spectral…
In this article, we construct the color-singlet-color-singlet type currents to study the scalar and axialvector $\Xi_{cc}\Sigma_c$ dibaryon states with QCD sum rules in details by taking into account both the dibaryon states and two-baryon…
Sum rules for products of two, three and four QCD currents are derived using chiral symmetry at infinite momentum in the large-N limit. These exact relations among meson decay constants, axialvector couplings and masses determine the…
It is argued that it is valid to use QCD sum rules to determine the scalar and pseudoscalar two-point functions at zero momentum, which in turn determine the ratio of the strange to non-strange quark condensates $R_{su} = \frac{<\bar{s}…
When studying tetraquark states using the method of QCD sum rules, we find some tetraquark currents, such as $\bar u_L \gamma_\mu d_L~\bar d_L \gamma^\mu u_L$ and $\bar u_L \gamma_\mu d_L~\bar d_R \gamma^\mu u_R$, etc. We calculate their…
Constituting the largest subset of multiquark states so far observed by experiment, tetraquark mesons carrying overall quark flavour quantum numbers identical to those of the (conventional) quark-antiquark mesons necessitate their…
We derive new QCD sum rules for the axial coupling constants by considering two-point correlation functions of the axial-vector currents in a one nucleon state. The QCD sum rules tell us that the axial coupling constants are expressed by…