Related papers: Scalar mesons as simple quark+antiquark states

The exploration of energies above the open-flavor threshold in the meson spectra has led to the appearance of unexpected states difficult to accommodate in the naive picture of a bound state of a quark and an antiquark. Many of such states…

While the light scalar mesons ($S_0$) are considered to be either ordinary $q\bar q$ or exotic tetraquark states, we investigate the semileptonic decays $D\to S_0 e^+\nu_e$, by taking into account the resonant effects of $S_0\to M_1 M_2$,…

Les We present a new perspective on the scalar meson puzzle from spontaneous breaking of chiral symmetry beyond BCS. We find that going beyond BCS does not produce a systematic shift of the hadron spectrum. We also show that coupled…

The decay rates and spectroscopy of the $D$ and $D_s$ mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type $V(r)=-{4/3}\frac{\alpha_s}{r}+A r^{\nu}$ with different choices of $\nu$. Numerical…

We study the spectrum of scalar-isoscalar excitations in the color-flavor locked phase of dense quark matter. The sigma meson in this phase appears as a four-quark state (of diquark and anti-diquark) with a well-defined mass and extremely…

We apply a quark interchange model to spin-dependent and exotic meson-meson scattering. The model includes the complete set of standard quark model forces, including OGE spin-orbit and tensor and scalar confinement spin-orbit. Scattering…

An effective Lagrangian model in a coupled channels framework is applied to extract nucleon resonance parameters. In the K-matrix approximation, we simultaneously analyze all the available data for the transitions from pi N to five possible…

The scalar mesons are established for a long time, but their nature is still an open question. In this paper, we investigate the potential of categorizing their $SU(3)_f$ representations via $J/\psi\to SV$ and $\gamma S$, offering a…

The properties of scalar quarks are studied, especially the formation of fermionic mesons with an anti-quark. On the basis of this theoretical investigation together with the experimental data, both from last year and from this year, of the…

Masses of open- and hidden-charm tetra-quark scalar mesons are studied in a new approach. As the result, newly estimated masses of hidden-charm sector are significantly lower than our earier ones by a naive quark counting. In particular,…

Analysis of the isoscalar S- and D-waves of processes pi-pi-> pi-pi, K-Kbar, eta-eta is carried out aimed at studying the status and QCD nature of scalar and tensor mesons below 2 GeV and 2.3 GeV, respectively. Assignment of these mesons to…

By scaling the parameters of meson-meson unitarized Chiral Perturbation Theory amplitudes according to the QCD large N_c rules, one can study the spectroscopic nature of light meson resonances. The scalars sigma, kappa f_0(980) and,…

We study the properties of charmed pseudoscalar and vector mesons in dense matter within a unitary meson-baryon coupled-channel model which incorporates heavy-quark spin symmetry. This is accomplished by extending the SU(3)…

We consider B to PS decays where P stands for pseudoscalar and S for a heavy (~1500 MeV) scalar meson. We achieve agreement with available experimental data -- which includes a two orders of magnitude hierarchy -- assuming the scalars…

Initiated by the recent observation of a flattened lineshape of $IJ^{PC}=00^{-+}$ around $1.4\sim 1.5$ GeV in the $K_S K_S \pi^0$ invariant mass spectrum by BESIII, we make a systematic partial wave analysis of $J/\psi \to\gamma\eta_X\to…

The light-quark non-strange scalar mesons a0(980), f0(980), f0(1370), a0(1450), f0(1500) and f0(1710) are of great interest as there is no generally accepted view of their structure which can encompass q-q-qbar-qbar, molecular, q-qbar and…

With usage of obvious mechanisms of quark currents the amplitudes of leptonic decaies of pseudoscalar mesons are investigated. The estimation for a constant of leptonic decay of the D+ meson is obtained, f_D+ ~ 0.23 GeV.

The existence of hadrons containing gluons as constituent particles (like hybrid mesons) will involve the necessity to admit an hadronic spectroscopy beyond the naive quark model. In the QGC model, the lowest J^{PC}= 1^{-+} hybrid mesons…

In this article, we take the point of view that the $0^{++}$ nonet mesons below $1 GeV$ are diquark-antidiquark states $(qq)_{\bar{3}}(\bar{q}\bar{q})_3$, and devote to determine their masses in the framework of the QCD sum rules approach…

Pion pion scattering is studied in a generalized linear sigma model which contains two scalar nonets (one of quark-antiquark type and the other of diquark-antidiquark type) and two corresponding pseudoscalar nonets. An interesting feature…