The light scalar nonets are studied using the QCD sum rules for the tetraquark operators. The operator product expansion for the correlators is calculated up to dimension 12 and this enables us to perform analyses retaining sufficient pole-dominance. To classify the light scalar nonets, we investigate the dependence on current quark mass and flavor dynamics. Especially, to examine the latter, w...

In this paper, using Monte Carlo Fortran code, we have obtained the binding energies for three different systems of diquark–antidiquark in distances from 0.01 to 15 nm. In [0.1 - 15] nm interval, we made use of Coulomb potential because in this interval, strong interaction is negligible. We have compared the binding energies of the systems with one another. The results of these comparisons...

The qq 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. The 0 light mesons and the new D states measured at different factories cannot be described as qq̄ pairs and a tetraquark structure is suggested.

It is suggested that the narrow meson state seen in the the SELEX experiment is a (cs̄ss̄) tetraquark state. Characteristics of other possible tetraquarks formed out of c and s quarks and antiquarks are considered. SELEX experiment has reported [1] a puzzling narrow meson state at a mass of 2632.6± 1.6 MeV/c which decays preferentially to D s (cs̄) + η(548) rather than to D(cd̄)+K or D(cū)+K. In th...

We investigate spin effects in four-quark systems consisting of two heavy anti-bottom quarks and two light up/down quarks. To this end we use the Born-Oppenheimer approximation. We utilize potentials of two static antiquarks in the presence of two quarks of finite mass computed via lattice QCD and solve a coupled-channel Schrödinger equation for the anti-bottom-anti-bottom separation. Without t...

The Coulomb gauge Hamiltonian model is used to calculate masses for selected J states consisting of exotic combinations of quarks and gluons: ggg glueballs (oddballs), qq̄g hybrid mesons and qq̄qq̄ tetraquark systems. An odderon Regge trajectory is computed for the J−− glueballs with intercept much smaller than the pomeron, explaining its nonobservation. The lowest 1 hybrid meson mass is found to ...

In this article, we study the mass spectrum of the scalar hidden charmed and bottomed tetraquark states with the QCD sum rules. The numerical results are compared with the corresponding ones from the potential quark model. PACS number: 12.39.Mk, 12.38.Lg

There exist heavy tetraquark states QQq̄q̄ in the heavy quark limit. These states are stable with respect to strong interactions and hence must decay weakly. It is shown that the semileptonic decay depends on a single Isgur– Wise form factor, which can be expressed in term of the Isgur–Wise form factors which govern the semileptonic decays of the Qqq and QQq baryons. Typeset using REVTEX 1 The po...

In the framework of an extended chromomagnetic model, we systematically study mass spectrum $S$-wave $qQ\bar{Q}\bar{Q}$ tetraquarks. Their spectra are mainly determined by color interaction. For $qc\bar{c}\bar{c}$, $qb\bar{c}\bar{c}$ and $qb\bar{b}\bar{b}$ tetraquarks, interaction favors color-sextet $\ket{(qQ)^{6_{c}}(\bar{Q}\bar{Q})^{\bar{6}_{c}}}$ configuration over color-triplet $\ket{(qQ)^...