Related papers: Confinement and cut-off: a model for the pion quar…
We discuss the most general form of the electromagnetic vertex of an off-shell pion. The framework of chiral perturbation theory is used to illustrate the representation dependence of the electromagnetic three-point Green's function. For…
In this paper scattering equivalences are used to simplify current operators in constituent quark models. The simplicity of the method is illustrated by applying it to a relativistic constituent quark model that fits the meson mass…
We investigate the role of the pion in Covariant Density Functional Theory. Starting from conventional Relativistic Mean Field (RMF) theory with a non-linear coupling of the $\sigma$-meson and without exchange terms we add pions with a…
A model for the pionic components of nuclear wave functions is obtained from light front dynamical calculations of binding energies and densities. The pionic effects are small enough to be consistent with measured nuclear di-muon production…
The leading-twist valence-quark distribution function in the pion is obtained at a low normalization scale of an order of the inverse average size of an instanton $\rho_c$. The momentum dependent quark mass and the quark-pion vertex are…
Pion transition form factor for the process $\gamma*\gamma*\to \pi^0$ at space-like values of photon momenta is calculated within the effective quark-meson model with the interaction induced by instanton exchange. The leading and…
We investigate the spin structure of the pion within the framework of the nonlocal chiral quark model from the instanton vacuum. We first evaluate the tensor form factors of the pion for the first and second moment (n=1,2) and compare it…
Pion scattering and electro-production amplitudes have been computed in a coupled-channel framework incorporating quasi-bound quark-model states, based on the Cloudy Bag model. All relevant low-lying nucleon resonances in the P33, P11, and…
We consider Compton scattering by a pion in the framework of chiral perturbation theory. We investigate off--shell effects in the s-- and u--channel pole diagrams. For that purpose we perform a field transformation which, in comparison with…
We evaluate Generalized Parton Distributions of the pion in two chiral quark models: the Spectral Quark Model and the Nambu-Jona-Lasinio model with a Pauli-Villars regularization. We proceed by the evaluation of double distributions through…
Compton scattering on the deuteron is studied in the framework of baryon chiral perturbation theory to third order in small momenta, for photon energies of order the pion mass. The scattering amplitude is a sum of one- and two-nucleon…
The new BABAR data on the pion-photon transition form factor arouses people's new interests on the determination of pion distribution amplitude. To explain the data, we take both the leading valence quark state's and the non-valence quark…
In the context of chiral SU(2) perturbation theory, pion-kaon scattering is analysed near the threshold to fourth chiral order. The scattering amplitude is calculated both in the relativistic framework and by using an approach similar to…
Recent developments in low energy pion physics are reviewed, emphasizing the strength of dispersion theory in this context. As an illustration of the method, I discuss some consequences of the forward dispersion relation obeyed by the…
We investigate the structure of constituent quarks and study implications for quark distribution functions of hadrons. Constituent quarks are constructed by dressing bare quarks with Goldstone bosons using the chiral quark model. We…
A scenario is investigated in which the leading-twist pion distribution amplitude phi_pi (x) is approximated by the pion decay constant f_pi for all essential values of the light-cone fraction x. A model for the light-front wave function…
We discuss the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the twist-2 and twist-3 distribution amplitudes of a pion. In particular, we exhibit that the pion twist-3…
We present results for the first two moments of the light-cone distribution amplitudes of the pion and kaon pseudo-scalar mesons and of the rho, K* and phi vector mesons. The calculations are performed on the RBC/UKQCD collaborations'…
Results of the Spectral Quark Model for the gravitational, electromagnetic, and transition form factors of the pion are discussed. In this model both the parton distribution amplitude and the parton distribution function are flat, in…
We analyze the power counting of the peripheral singlet partial waves in nucleon-nucleon scattering. In agreement with conventional wisdom, we find that pion exchanges are perturbative in the peripheral singlets. We quantify from the…