Related papers: N-Delta axial transition form factors
The vector and axial pion-photon transition distribution amplitudes are analyzed in the Spectral Quark Model. We proceed by the evaluation of double distributions through the use of a manifestly covariant calculation based on the alpha…
The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to study semiclassical production of pions in the central region. The mechanism is related to the isospin-uniform…
The pseudo scalar form factor, which represents the pseudo scalar quark density distribution due to finite quark masses on the nucleon, is shown to manifest itself with the induced pseudo scalar form factor in the $L_0^+$ amplitude for the…
The CLEO experimental data on the $\pi\gamma$ transition are analyzed to next-to-leading order accuracy in QCD perturbation theory using light-cone QCD sum rules. By processing these data along the lines proposed by Schmedding and Yakovlev,…
We revisit the definition of the leading-twist chiral-even generalized parton distributions (GPDs) for $N \to \Delta$ baryon transitions. We identify and address deficiencies in previous definitions of the transition GPDs inspired by the…
Detailed predictions for the scaled pion-photon transition form factor are given, derived with the method of light-cone sum rules and using pion distribution amplitudes with two and three Gegenbauer coefficients obtained from QCD sum rules…
We point out that the $\Delta\pi$ component of the nucleon wave function is vital to the interpretation of the recent H1 data for leading baryon production. While the $n/p$ ratio is equal to two with the $N\pi$ component alone, the…
We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of pseudoscalar pion currents. The essential instanton contribution is reanalysed with account for present more…
Form factors are quantities that involve both asymptotic on-shell states and gauge invariant operators. They provide a natural bridge between on-shell amplitudes and off-shell correlation functions of operators, thus allowing us to use…
The four N to $\Delta$ axial transition form factors are evaluated using quenched QCD, using two flavors of dynamical Wilson fermions and using domain wall valence fermions on three-flavor MILC configurations for pion masses down to 360…
We study the pion electromagnetic form factor in the modulus squared dispersion relation, and do the model independent extraction of the most important nonperturbative parameters in pion light-cone distribution amplitude. The motivation of…
We study elastic N$\alpha $ scattering and produce a quantitative correlation between the range of the effective potential and the energy of the system. This allows the identification of the waves and energies for which the scattering may…
We discuss the two-pion exchange potential which emerges from a box diagram with one nucleon (the spectator) restricted to its mass shell, and the other nucleon line replaced by a subtracted, covariant $\pi N$ scattering amplitude which…
The general features of baryon form factors calculated with point form kinematics are derived. With point form kinematics and spectator currents hadronic form factors are functions of $\eta:={1\over 4}(v_{out}-v_{in})^2$ and, over a range…
We have performed a theoretical study of the axial Nucleon to Delta(1232) ($N\to\Delta$) transition form factors up to one-loop order in covariant baryon chiral perturbation theory within a formalism in which the unphysical spin-1/2…
In my talk I discuss the theoretical and experimental status of the pion distribution amplitude (DA). I show that the QCD sum rule method with nonlocal condensates (NLC) for the pion DA gives us admissible sets (bunches) of DAs for each…
We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz…
The pion-nucleon amplitude is considered in the vicinity of the elastic scattering threshold within a relativistic dynamical model dressing the pi N N and pi N Delta vertices self-consistently with an infinite number of meson loops. The…
We present covariant predictions of relativistic constituent quark models for pi and eta decay widths of N and Delta resonances. The results are calculated for a model decay operator within the point-form spectator approximation. It is…
We present a relativistic procedure for the chiral expansion of the two-pion exchange component of the $NN$ potential, which emphasizes the role of intermediate $\pi N$ subamplitudes. The relationship between power counting in $\pi N$ and…