Related papers: Axial exchange currents and nucleon spin
The spin and orbital angular momentum carried by different quark flavors in the nucleon are calculated in the SU(3) chiral quark model with symmetry-breaking. The model is extended to all octet and decuplet baryons. In this model, the…
In the Standard Model of particle physics, the axial current is not conserved, due both to fermion masses and to the axial anomaly. Using perturbative quantum chromodynamics, we calculate matrix elements of the local and non-local axial…
The two-pion exchange interaction between constituent quarks is shown to enhance the effect of the the isospin dependent spin-spin component of the one-pion exchange interaction, and to cancel out its tensor component. It therefore provides…
New relations between the quark spin-flavor contents of the nucleon and axial weak coupling constants are obtained in the chiral quark model with both SU(3) and U(1)-breaking effects. Using the nonsinglet spin combinations, $\Delta_3$ and…
The improved quark mass density- dependent model which includes the coupling between the quarks and a non-linear scalar field is presented. Numerical analysis of solutions of the model is performed over a wide range of parameters. The wave…
We have analyzed axial-vector current-current correlation functions between one-nucleon states to calculate the singlet axial-vector coupling constant of the nucleon. The octet-octet and the octet-singlet current correlators, investigated…
We study the interactions of an elementary pion with a nucleon made of constituent quarks and show that the enforcement of chiral symmetry requires the use of a two-body operator, whose form does not depend on the choice of the pion-quark…
The relativistic constituent quark model of low-energy quantum chromodynamics is found to yield a consistent picture of the electroweak structure of the nucleons. Notably, the electromagnetic and axial form factors of both the proton and…
Unusual constituent quark axial current couplings to light vector mesons, $\rho$ and $\omega$, are derived in the vacuum and under weak magnetic field by considering a quark-antiquark interaction mediated by a non perturbative gluon…
We calculate shell-model matrix elements of the axial-charge exchange current operators that have been obtained up to the next-to-leading order from heavy-fermion chiral perturbation theory. It is found that loop corrections to the soft…
We use a continuum quark+diquark approach to the nucleon bound-state problem in relativistic quantum field theory to deliver parameter-free predictions for the nucleon axial and induced pseudoscalar form factors, $G_A$ and $G_P$, and unify…
We present results for the nucleon magnetic moments in the context of an extended chiral constituent quark model based on the mechanism of the Goldstone boson exchange, as suggested by the spontaneous breaking of chiral symmetry in QCD. The…
This study explores the role of nucleon exchange for the generation of the fission fragment angular momenta. For a number of typical fission cases, samples of 10,000 shape evolutions are generated by Langevin simulation and, subsequently,…
Quark-model descriptions of the nucleon-nucleon interaction contain two main ingredients, a quark-exchange mechanism for the short-range repulsion and meson-exchanges for the medium- and long-range parts of the interaction. We point out the…
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion…
The three flavor soliton approach for baryons is utilized to discuss effects of flavor symmetry breaking in the baryon wave--functions on axial current matrix elements. The flavor content of the singlet axial current matrix elements, that…
We apply the perturbative chiral quark model (PCQM) at one loop to analyze the axial form factor of the nucleon. This chiral quark model is based on an effective Lagrangian, where baryons are described by relativistic valence quarks and a…
The axial form factor G_A of the nucleon is investigated for the Goldstone-boson-exchange constituent quark model using the point-form approach to relativistic quantum mechanics. The results, being covariant, show large contributions from…
We present a charged-current quasielastic neutrino-nucleus scattering model based on an unfactorized representation of the spectral function, employing relativistic momentum distributions for bound nucleons and the relativistic…
We derive new QCD sum rules for the axial coupling constants by considering two-point correlation functions of the axial-vector currents in a one nucleon state. The QCD sum rules tell us that the axial coupling constants are expressed by…