Related papers: A chiral qbarqbarqq nonet?
In this article, we assume that the nonet scalar mesons below $1\,\rm{ GeV}$ are the two-quark-tetraquark mixed states and study their masses and pole residues using the QCD sum rules. In calculation, we take into account the vacuum…
Since the early days of QCD, it has been argued that inside hadrons quarks organise into substructures. Among those, popular pictures of various phenomena (including exotica and colour superconductivity) give a prominent role to diquarks,…
The essential points and physical backgrounds of the covariant level-classification scheme, recently proposed by us, are reviewed: In this scheme the general composite hadrons are classified as the multiplets with the U(12)SF * O(3,1)…
Following the re-establishment of the \sigma(600) and the \kappa(900), the light scalar mesons a_0(980) and f_0(980) together with the \sigma(600) and the \kappa(900) are considered as the chiral scalar partner of pseudoscalar nonet in…
In this talk I summarize recent findings around the description of axial vector mesons as dynamically generated states from the interaction of pseudoscalar mesons and vector mesons, dedicating some attention to the two $K_1(1270)$ states.…
A quark model, which reproduces the ground-state mesons and baryons, i.e., the threshold energies, is applied to the $qqqc\bar c$ configurations, where $q$ is a light quark and~$c$ the charmed quark. In the calculation, several open…
The tetraquark assignement for light scalar states below 1 GeV is discussed on the light of strong decays. The next-to-leading order in the large-N expansion for the strong decays is considered. Mixing with quarkonia states above 1 GeV is…
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…
With the discovery of some hidden-charm pentaquark resonances by the LHCb Collaboration, investigations of pentaquark states containing heavy quarks have aroused the interest of theorists. We study herein $qqq\bar{q}Q$ ($q = u$ or $d$,…
The suggestion by Jaffe that if $\sigma$ is a light $q^{2}\bar{q}^{2}$ state $0^{++}$ then even the fundamental chiral transformation properties of the $\sigma$ becomes {\bf unclear}, has stimulated much interest. Adler pointed out that in…
The nonleptonic weak decays of charmed mesons into a scalar meson and a pseudoscalar meson are studied. The scalar mesons under consideration are $\sigma$ [or $f_0(600)$], $\kappa$, $f_0(980)$, $a_0(980)$ and $K^*_0(1430)$. A consistent…
Additional broader I=0 states in the KN channel near $\Theta^+$(1540) are expected in many models, making the absence of any signature in the K$^+$-deuteron scattering data even more puzzling. In an ideal "three-body" picture the $\Theta$…
As has been confirmed meanwhile by lattice-QCD calculations (see e.g. hep-lat/0702023), the confinement spectrum of non-exotic quark-antiquark systems has its ground state for scalar mesons well above 1 GeV in the Resonance Spectrum…
We calculate the decay rate of light scalar mesons, using a diquark chiral effective theory, recently proposed to describe exotic hadrons. In the effective theory the light scalar mesons are postulated to be bound states of diquark and…
The role of the quark condensate in low-energy QCD and its behaviour in nuclear matter are discussed. Partial restoration of chiral symmetry, as indicated by a reduction of the quark condensate in matter, could significantly alter the…
We present a detailed study of lowest-lying $q^{2}\bar{q}^{2}$ hadrons in quenched improved anisotropic lattice QCD. Using the $\pi\pi$ and diquark-antidiquark local and smeared operators, we attempt to isolate the signal for…
Recently, Belle\uppercase\expandafter{\romannumeral2} Collaboration firstly reported a new resonance $\omega\chi_{bJ}$ in the processes of $e^{+}e^{-} \rightarrow \omega\chi_{bJ}$ at center-of-mass energies $\sqrt{s}=10.745$ GeV. Given the…
Inspired by recent measurement of possible fully charmed tetraquarks in LHCb Collaboration, we investigate the mass spectra of fully heavy tetraquarks $QQ \bar Q \bar Q$ in an extended relativized quark model. Our estimations indicate that…
We show that vector-like quarks in the fundamental or higher-dimensional representations of QCD can generate the electro-weak scale in a phenomenologically viable way by chiral symmetry breaking condensates. The thereby generated scales are…
The chiral symmetry is applied to an extended constituent quark potential model. With random phase approximation (RPA), the model comprises sea quark excitations. To obtain the pseudoscalar $\pi$ meson as a Goldstone boson, the quark…