Related papers: Chiral Symmetry and Scalars
Meson spin splittings are examined within an effective Coulomb gauge QCD Hamiltonian incorporating chiral symmetry and a transverse hyperfine interaction necessary for heavy quarks. For light and heavy quarkonium systems the…
A new unitarization approach is discussed and applied to study the elastic $\pi K$ scattering process. The existence of the light $\kappa$ resonance is firmly established if the scattering length in the I=1/2 channel does not deviate too…
The light scalar meson sigma(600) is known to appear at low excitation energy with very large width on top of continuum states. We investigate it in the QCD sum rule as an example of resonance structures appearing above the corresponding…
Re-analyzing the old phase shift data of I=0, \pi\pi (I=1/2, K\pi) scattering, we show an evidence for existence of the \sigma-particle (\kappa-particle) with a comparatively light mass, which has been missing for a long time: In the…
Half a century of work on the light scalar mesons $f_0(500)$, $f_0(980)$, $K_0^\star(700)$, and $a_0(980)$ is briefly reviewed. After summarising all light scalar candidates in the Review of Particle Physics since 1963, a selection of…
I propose a controlled approximation to QCD-like theories with massless quarks by employing supersymmetric QCD perturbed by anomaly-mediated supersymmetry breaking. They have identical massless particle contents. Thanks to the…
We first discuss the theoretical and phenomenological significance of the sigma meson ($\sigma$) in QCD. It is indicated that if the collective modes with the mass 500-600 MeV exists in the $I=J=0$ channel, various empirical facts in hadron…
Chiral symmetry represents a fundamental concept lying at the core of particle and nuclear physics. Its spontaneous breaking in vacuum can be exploited to distinguish chiral hadronic partners, whose masses differ. In fact, the features of…
The ${q}\bar{q}$ 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. The new $D$ states measured at different…
After a brief summary of the QCD phase structure with light quarks, we discuss two recent developments on in-medium hadrons. First topic is the sigma-meson which is a fluctuation of the chiral order parameter \bar{q}q. Although sigma is at…
We discuss the possible influence of fundamental QCD properties such as spontaneous chiral symmetry breaking and nucleon substructure on nuclear matter properties. We propose a chiral version of the relativistic $\sigma-\omega$ model in…
The following topics are considered. 1) Confinement, chiral dynamics, and light scalar mesons. 2) Chiral shielding of the \sigma(600) 3)The \phi meson radiative decays about nature of light scalar resonances. 4) The J/\psi decays about…
Within the increasing experimental evidence of the existence of the I=0 scalar low mass and wide \sigma meson, we review the {\it first} analysis of its quark and gluon substructure from QCD spectral sum rules and some low-energy theorems.…
It is pointed out that the hadron spectroscopy should be a study of the structure of the QCD vacuum, low-energy elementary excitations on top of which are hadrons. Concentrating on the dynamical breaking of the chiral symmetry in the QCD…
The quark-level linear sigma model is revisited, in particular concerning the identification of the f_0(400-1200) (or \sigma(600)) scalar meson as the chiral partner of the pion. We demonstrate the predictive power of the linear sigma model…
The non-perturbative Schwinger-Dyson equation is used to show that chiral symmetry is dynamically broken in QED at weak gauge couplings when an external uniform magnetic field is present. A complete analysis of this phenomenon may shed…
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…
The recent experimental data of both pipi / Kpi scattering and production processes, suggesting the existence of scalar sigma and kappa mesons, are reviewed. In many pipi /Kpi production processes the direct effects of their productions are…
Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate…
I present a mini-review of the masses and couplings of the bare (unmixed) light scalar mesons : $\bar qq, (\overline{qq})(qq), (\bar qq)(\bar qq), gg$ from QCD spectral sum rules (QSSR) and low-energy theorems (LET) which we compare with…