Related papers: Comment on "$\sigma$-meson: Four-quark versus two-…
Decays of the fully beauty four-quark structures $X_{\mathrm{4b}}$ and $T_{ \mathrm{4b}}$ to $B$ meson pairs are investigated in the framework of QCD three-point sum rule method. We model the scalar exotic mesons $X_{\mathrm{4b }}$ and…
We perform a constituent quark model analysis for the masses of the doubly heavy tetraquark states $T_{QQ}$ after we fix the parameters to fit the masses of the newly observed $\Xi_{cc}^{++}$ and hadrons involving heavy quarks relevant to…
In this feature article we summarise and highlight aspects of the treatment of four-quark states with functional methods. Model approaches to those exotic mesons almost inevitably have to assume certain internal structures, e.g. by grouping…
We study the spectra of the doubly charmed tetraquark states in a diquark-antidiquark model. The doubly charmed tetraquark states form an antitriplet and a sextet configurations according to flavor SU(3) symmetry. For the tetraquark state…
The study of the fully heavy tetraquark state helps to better understand the characteristics of compact exotic hadrons formed by quarks and gluons. In this work, we systematically investigate the mass spectra and decay channels of fully…
Focusing on the continuum meson bound-state problem, a novel method is used to calculate closed-form Bethe-Salpeter kernels that are symmetry consistent with any reasonable gluon-quark vertex, $\Gamma_\nu$, and therewith deliver a…
We study the two point-function for the scalar mesons $\sigma, \kappa, f_0(980)$ and $a_0(980)$ as diquak-antidiquark states. We also study the decays of these mesons into $\pi\pi$, $K\pi$ and $K\bar{K}$. We found that the couplings are…
We consider the relative decay rates of B0 and Bs mesons into a J\psi\ plus a light scalar meson either the f0(500) (\sigma) or the f0(980). We show that it is possible to distinguish between the quark content of the scalars being…
The mass spectrum of heavy pseudoscalar mesons, described as quark-antiquark bound systems, is considered within the Bethe-Salpeter formalism with momentum dependent masses of the constituents. This dependence is found by solving the…
In the heavy quark limit, the heavy baryons \omega_{Q}^{(*)} (\omega could be \Sigma, \Xi or \Omega and Q=b or c) are regarded as composed of a heavy quark and an axial vector, light diquark with good spin and isospin quantum numbers. Based…
We interpret the $X_1(2900)$ as an $S$-wave $\bar{D}_1K$ molecular state in the Bethe-Salpeter equation approach with the ladder and instantaneous approximations for the kernel. By solving the Bethe-Salpeter equation numerically with the…
Treating the $X(4140)$ as a compact $J^{PC}=1^{++}$ $cs\bar{c}\bar{s}$ state and using its mass as a reference scale, we systematically estimate the masses of doubly heavy tetraquark states $QQ\bar{q}\bar{q}$ where $Q=c,b$ and $q=u,d,s$.…
We give a review of the calculations of the masses of tetraquarks with two and four heavy quarks in the framework of the relativistic quark model based on the quasipotential approach and QCD. The diquark-antidiquark picture of heavy…
In a modified chromomagnetic interaction model, assuming $X(4140)$ to be the lowest $1^{++}$ $cs\bar{c}\bar{s}$ tetraquark and treating it as the reference state, we systematically investigated the masses of the triply-heavy tetraquark…
Starting from a path integral representation of appropriate 4-point and 2-point gauge invariant Green functions and from the "Modified Area Law" model for the evaluation of the Wilson loop, a q \bar q Bethe-Salpeter like equation and a…
We treat baryons as bound states of scalar or axialvector diquarks and a constituent quark which interact through quark exchange. We obtain fully four-dimensional wave functions for both octet and decuplet baryons as solutions of the…
Motivated by the discovery of several charm states exhibiting tetraquark-like characteristics at BESIII and LHCb, this study investigates the spectroscopy and decay properties of D mesons and tetraquark states with quark content…
I review some selected aspects of the phenomenology of multiquark states discovered in high energy experiments. They have four valence quarks (called tetraquarks) and two of them are found to have five valence quarks (called pentaquarks),…
We treat baryons as bound states of scalar or axialvector diquarks and a constituent quark which interact through quark exchange. This description results as an approximation to the relativistic Faddeev equation for three quarks which…
In the diquark-quark model of the nucleon including scalar and axialvector diquarks we compare solutions of the ladder Bethe-Salpeter equation in the instantaneous Salpeter approximation and in the fully covariant (i.e. four-dimensional)…