Related papers: Scalar mesons: fifty years of challenging the quar…
In this article, we take the point of view that the scalar mesons $ f_0(980)$ and $a_0(980)$ 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…
Attention is paid to the production mechanisms of light scalars that reveal their nature. We reveal the chiral shielding of the \sigma(600) meson. We show that the kaon loop mechanism of the \phi radiative decays, ratified by experiment,…
We first briefly review a treatment of the scalars in meson meson scattering based on a non-linear chiral Lagrangian, with unitarity implemented by a "local" modification of the scalar propagators. It is shown that the main results are…
We describe a four-parameter model for non-exotic meson-meson scattering, which accommodates all non-exotic mesons, hence also the light scalar mesons, as resonances and bound states characterised by complex singularities of the scattering…
We calculate low-energy meson decay processes and pion-pion scattering lengths in a globally chirally invariant two-flavour linear sigma model exploring the quark content of the scalar mesons f(0)(600) and a(0)(980), as well as f(0)(1370)…
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…
Masses and widths of the four light scalar mesons $\sigma$, $\kappa$, $a_0$(980) and $f_0$(980) may be reproduced in a model where mesons scatter via a $q\bar{q}$ loop. A transition potential is used to couple mesons to $q\bar{q}$ at a…
We study the possibility that the light scalar mesons are (qbar qbar q q) states rather than (qbar q). We perform a lattice QCD calculation of pseudoscalar meson scattering amplitudes, ignoring quark loops and quark annihilation, and find…
We study the dynamical generation of scalar mesons in the light quark sector ($q\in\{u,d,s\}$) and calculate the masses and widths for the $f_0(500),a_0(980)$ and $f_0(980)$. To this end we study the mixing of conventional $q\bar{q}$ and…
We discuss the effect of the instanton induced, six-fermion effective Lagrangian on the decays of the lightest scalar mesons in the diquark--antidiquark picture. This addition allows for a remarkably good description of light scalar meson…
The hadronic charmless B decays into a scalar meson and a pseudoscalar meson are studied within the framework of QCD factorization. Although the light scalar mesons $f_0(980)$ and $a_0(980)$ are widely perceived as primarily the four-quark…
I describe some insight obtained from a lattice calculation on the possibility that the light scalar mesons are \qbar^2 q^2 states rather than \qbar q. First I review some general features of \qbar^2 q^2 states in QCD inspired quark models.…
The structure of the light scalar mesons is elucidated by the investigation of the S-matrix poles and the q-qbar spectral density in a coupled channel model that includes pi-pi, K-Kbar and q-qbar channels. It is shown that the dynamical…
Non-leptonic D meson decays may provide a reliable testbed for the multiquark interpretation of light scalar mesons. In this letter we consider D_s decay and show that a 4-quark f_0(980) meson could induce a decay pattern, which is…
We study the semileptonic decays of $D_{s}^{+}$, $D^{+}$, and $D^{0}$ mesons into the light scalar mesons [$f_{0} (500)$, $K_{0}^{\ast} (800)$, $f_{0} (980)$, and $a_{0}(980)$] and the light vector mesons [$\rho (770)$, $\omega (782)$,…
The assignments of the isoscalar scalar mesons f0(980), f0(1370), and f0(1500) in terms of their qqbar substructure is still a matter of heated dispute. Here we employ the weak and electromagnetic decays D(s)(+) to f0+pi(+) and f0…
We study the light scalar mesons in the QCD sum rule. We construct both the diquark-antidiquark currents $(qq)(\bar q \bar q)$ and the meson-meson currents $(\bar qq)(\bar qq)$. We find that there are five independent currents for both…
I review a proposed pattern of the light scalar mesons with q\bar{q} mesons and glueball above 1 GeV and tetraquark mesoniums below 1 GeV. Several challenges and caveats of calculating these light scalar mesons with dynamical fermions are…
The light quark $uds$ mesons have been a foundation of our understanding of the strong interaction for decades. New experiments with modern detectors and large data sets are furthering our understanding of the spectrum and dynamics of these…
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 $S_0\to M_1 M_2$,…