Related papers: Sea-quark effects in the pion charge form factor
The kaon electromagnetic (e.m.) form factor is reviewed considering a light-front constituent quark model. In this approach, it is discussed the relevance of the quark-antiquark pair terms for the full covariance of the e.m. current. It is…
The presently experimentally interesting form factor for the anomalous process gamma -> pi^+ pi^0 pi^- is calculated as the quark "box"-amplitude where the intermediate fermion loop is the one of constituent quarks with the pseudoscalar…
We employ a dispersion relation that allows to recover the phase of the electromagnetic form factor of the pion from its absolute value above threshold. Compared to alternative approaches building on the phase, this approach builds on…
We compute the electromagnetic form factor of a "pion" with mass m_pi=330MeV at low values of Q^2\equiv -q^2, where q is the momentum transfer. The computations are performed in a lattice simulation using an ensemble of the RBC/UKQCD…
Sea quark contributions to the scalar density and the axial current matrix elements of the nucleon are studied in lattice qcd with two flavours of dynamical wilson fermions. the results are compared to trends in heavy quark mass expansions,…
The nucleon's peripheral transverse charge and magnetization densities are computed in chiral effective field theory. The densities are represented in first-quantized form, as overlap integrals of chiral light-front wave functions…
The $\gamma^\ast \gamma \to \pi^0$ transition form factor, $G(Q^2)$, is computed on the entire domain of spacelike momenta using a continuum approach to the two valence-body bound-state problem in relativistic quantum field theory: the…
The pion electromagnetic form factor F_{\pi}(Q^{2}) is calculated at the leading order of pQCD using the running coupling constant (\alpha_{S}(Q^{2}(1-x)(1-y))) approach. The resummed expression for F_{\pi}(Q^{2}) is found. It is shown that…
We study the weak interaction axial form factors of the octet baryons, within the covariant spectator quark model, focusing on the dependence of four-momentum transfer squared, Q^2. In our model the axial form factors G_A(Q^2) (axial-vector…
We describe the calculation of the $B\rightarrow \pi$ hadronic matrix element from operator product expansion near the light-cone in QCD. In the resulting sum rules, the form factors $f^+$ and $F_0$ determining this matrix element are…
Inspired by light-front holography, we compute the pion mass, charge radius, decay constant, electromagnetic form factor and electromagnetic transition form factor. To do so, we model the longitudinal quark dynamics using potentials due to…
We report a new determination of the strange quark contribution to the proton's magnetic form factor at a four-momentum transfer Q2 = 0.1 (GeV/c)^2 from parity-violating e-p elastic scattering. The result uses a revised analysis of data…
We develop a relativistic quark model for pion structure, which incorporates the non-trivial structure of the vacuum of Quantum Chromodynamics as modelled by instantons. Pions are boundstates of quarks and the strong quark-pion vertex is…
Effects of charge symmetry breaking associated with the $u$ and $d$ quark mass difference in the elastic form factors of the pion and kaon are presented. We use a confining version of the Nambu--Jona-Lasinio model. The pion and kaon are…
A new picture is given of generalized parton distributions probed in experiments in which the probe scale $Q^{2}$ and the momentum transfer $\DD^{2}$ are well separated. Application of this picture to the $Q^{2}$ dependence of the form…
We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of axial-vector pion currents. The theoretical predictions for Q^2-dependence of pion form factor are in good…
The H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F_pi) was extracted from the data by comparing the…
We present a brief survey of some results on electroweak properties of composite systems that are obtained in the frameworks of our version of the instant form of relativistic quantum mechanics (RQM). Our approach describes well the $\pi$-…
It is shown that the dynamical observables calculated with the point form relativistic quantum mechanics incorporate effects of particle-antiparticle creation from the vacuum by interactions. The electromagnetic observables obtained with…
We compute the Kl3 and pion form factors using partially twisted boundary conditions. The twists are chosen so that the Kl3 form factors are calculated directly at zero momentum transfer (q^2=0), removing the need for a q^2 interpolation,…