Related papers: Scalar mesons above and below 1 GeV
Calculations in unquenched QCD for the scalar glueball spectrum have confirmed previous results of Gluodynamics finding a glueball at ~ 1750 MeV. I analyze the implications of this discovery from the point of view of glueball-meson mixing…
The observed mass pattern of scalar resonances below 1 GeV gives preference to the tetraquark assignment over the conventional $\bar qq$ assignment for these states. We present a search for tetraquarks with isospins 0,1/2,1 in lattice QCD,…
Within a nonlinear chiral Lagrangian framework, the underlying mixings among quark-antiquark, four-quark and glue components of $f_0(1500)$ and $f_0(1710)$ are studied in a global picture that includes all isosinglet scalar mesons below 2…
Scalar mesons are a key expression of the infrared regime of QCD. The lightest of these is the $\sigma$. Now that its pole in the complex energy plane has been precisely located, we can ask whether this state is transiently ${\bar q}q$ or…
We resume the investigation of the ground-state pseudoscalar glueball, $J^{PC}=0^{-+}$, by computing its two- and three-body decays into vector and axial-vector quark-antiquark meson fields additional to scalar and pseudoscalar mesons…
We present a chiral effective model which exhibits all the known symmetry features of the QCD Lagrangian. The extended Linear Sigma Model (eLSM) includes (pseudo-)scalar and (axial-) vector mesons, glueballs, and baryons. It has proven to…
We show that under a number of rather plausible assumptions QCD spectrum may contain a number of mesons which have not been predicted or observed. Such states will have the quantum numbers of two existing mesons and masses very close to the…
We present systematic and improved estimates of the masses and couplings of the $(0^-)$ and $(1^-)$ $T_{QQ\bar q\bar q'}$ states ($Q= c,b;q,q'= u,d,s$) using QCD Laplace sum rules (LSR) and their ratios R within $\tau$ and $t_c$-stabilities…
The scalar mesons in the 1 GeV region constitute the Higgs sector of the strong interactions. They are responsible for the masses of all light flavour hadrons. However, the composition of these scalar states is far from clear, despite…
According to the QCD expectations the lightest glueball should be a scalar particle (J^{PC}=0^{++}). Different scenarios have been considered for a classification of these states but -- despite considerable progress in recent years -- the…
We study the spectrum of scalar glueballs in SQCD-like theories whose gravity description is in terms of Nc D5 color branes wrapped on an S^2 inside a CY3-fold, and Nf backreacting D5 flavor branes wrapped on a non-compact two-cycle inside…
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…
We study N and $\Delta$ hidden-charm baryon resonances that are generated dynamically from the s-wave interaction of pseudoscalar and vector mesons with $1/2^+$ and $3/2^+$ baryons. We use a unitary coupled-channels model that fulfills…
The spectrum of two-particle bound states is investigated within a relativistic quantum-field model of interacting quarks and gluons confined analytically. The hadronization process of mesons and glueballs is described by using the…
The QCD-vacuum is characterized by the Higgs phenomenon for colored scalar fields. In this dual picture the gluons appear as the octet of vector mesons. Also quarks and baryons are identified. Gluon-meson and quark-baryon duality can…
We studied meson-meson interactions using the 't Hooft model, which represents QCD in 1+1 dimensions and assumes a large number of colors ($N_c$). The dominant interactions in this large $N_c$ limit are generated by quark exchange. Our…
We discuss how the lightest scalars, in particular the broad sigma resonance, can be understood as unitarized (qbar q) states within a unitarized quark model (UQM). The bare (qbar q) scalars are strongly distorted by hadronic mass shifts,…
An effective meson Lagrangian including a scalar glueball is constructed on the base of $U(3)\times U(3)$ chiral symmetry. The glueball is introduced into the meson Lagrangian by using the principle of scale invariance of an effective…
Scalar mesons are a key expression of the strong coupling regime of QCD. How those with $I_3=0$ couple to two photons supplies important information about which is transiently ${\bar q}q$ or ${\bar {qq}} qq$ or multi-meson molecule or…
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,…