Related papers: Sigma-Meson and Confinement Singularity
Compton scattering by the proton has been measured using the tagged-photon facility at MAMI (Mainz) and the large-acceptance arrangement LARA. The new data are interpreted in terms of dispersion theory based on the SAID-SM99K…
A light-cone QCD-inspired model, with the mass squared operator consisting of a harmonic oscillator potential as confinement and a Dirac-delta interaction, is used to study the S-wave meson spectra. The two parameters of the harmonic…
In this work, the complete one loop calculation of meson-meson scattering amplitudes within U(3)\otimes U(3) chiral perturbation theory with explicit resonance states is carried out for the first time. Partial waves are unitarized from the…
We have performed a systematical calculation of the pion ($\pi, K, \eta$) and heavy pseudoscalar meson S-wave scattering lengths up to ${\cal O}(p^3)$ in the chiral perturbation theory in the heavy quark symmetry limit. With the three…
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…
The first part of this report reviews recent developments at the interface between lattice work on QCD with light dynamical quarks, effective field theory and low energy precision experiments. Then I discuss how dispersion theory can be…
We study the spin-exotic $J^{PC} = 1^{-+}$ amplitude in single-diffractive dissociation of 190 GeV$/c$ pions into $\pi^-\pi^-\pi^+$ using a hydrogen target and confirm the $\pi_1(1600) \to \rho(770) \pi$ amplitude, which interferes with a…
By separating data points close to a resonance into intervals, and fitting all possible intervals to a simple pole with constant coherently added background, we obtained a substantial number of convergent fits. After a carefully chosen set…
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 analyze the $K^-p\to K^+\Xi^-$ and $K^-p\to K^0\Xi^0$ processes in the energy region $1.8<\sqrt{s}<2.8$ GeV within an effective Lagrangian approach. The $\Lambda(1800)$ and $\Sigma(2250)$ resonances, along with the ground states $\Sigma$…
Whether the $\sigma-meson$ ($f_0(600)$) exists as a real particle is a long-standing problem in both particle physics and nuclear physics. In this work, we analyze the deuteron binding energy in the linear $\sigma$ model and by fitting the…
We study the four-body decays $J/\psi\to N {\bar N}$ {\it meson meson} using a chiral unitary approach to account for the meson meson final state interaction (FSI). The calculation of the $J/\psi\to N \bar N \pi^+ \pi^-$ process properly…
We calculate the T-matrices of pseudoscalar meson octet-baryon scattering to one-loop order in SU(3) heavy baryon chiral perturbation theory. The pertinent combinations of low-energy constants are determined by fitting to phase shifts of…
Masses of the lowest multiplets of c,b-mesons in S- and P-wave states with quantum numbers JPC: 0-+, 1--, 0++, 1+-, 1++, 2++ are obtained with the help of dispersion N/D method of heavy quark effective theory. The results are in a good…
The low-energy scattering properties of two aligned identical bosonic and identical fermionic dipoles are analyzed. Generalized scattering lengths are determined as functions of the dipole moment and the scattering energy. Near resonance,…
The flavour and glue structure of the light scalar mesons in QCD are probed by studying the couplings of the I=0 mesons $\sigma(600)$ and $f_0(980)$ to the operators $\bar{q}q$, $\alpha_s G^2$ and to two photons. The Roy dispersive…
In this article, we study the structure of the \rho meson in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with a confining effective potential. The u and d quark propagators get…
We review our analysis of $\pi K$ scattering using forward dispersion relations. The method yields a set of simple parameterizations that are compatible with forward dispersion relations up to 1.6 GeV while still describing the data. Once…
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…
Using the fact that the contribution of the states with isospin I=0 in the difference of the amplitudes of the processes \gamma \gamma->\pi^+\pi^- and \gamma\gamma->\pi^0\pi^0 is very small, we have analyzed the dispersion sum rules for the…