Search results for "Pion decay constant"
showing 5 items of 15 documents
Non local lagrangians(I): the pion
2005
We define a family of non local and chirally symmetric low energy lagrangians motivated by theoretical studies on Quantum Chromodynamics. These models lead to quark propagators with non trivial momentum dependencies. We define the formalism for two body bound states and apply it to the pion. We study the coupling of the photon and W bosons with special attention to the implementation of local gauge invariance. We calculate the pion decay constant recovering the Goldberger-Treiman and the Gell-Mann-Oakes-Renner relations. We recover a form of the axial current consistent with PCAC. Finally we study the pion form factor and we construct the operators involved in its parton distribution.
Pionic effects in deep inelastic scattering off nuclei
1992
The structure functions calculated in the Chiral bag model reproduce quite well, after appropriate perturbative evolution to large energy scales, the experimental data. We use these results to interpret the structure of the $EMC$ data as a quenching of the pion decay constant due to the in medium behavior of the nucleon. This explanation supports recent proposals of this phenomenon whose origin is the scale invariance of the $QCD$ lagrangian.
Quark gap equation with non-Abelian Ball-Chiu vertex
2018
The full quark-gluon vertex is a crucial ingredient for the dynamical generation of a constituent quark mass from the standard quark gap equation, and its non-transverse part may be determined exactly from the nonlinear Slavnov-Taylor identity that it satisfies. The resulting expression involves not only the quark propagator, but also the ghost dressing function and the quark-ghost kernel, and constitutes the non-abelian extension of the so-called "Ball-Chiu vertex", known from QED. In the present work we carry out a detailed study of the impact of this vertex on the gap equation and the quark masses generated from it, putting particular emphasis on the contributions directly related with t…
Quark gap equation within the analytic approach to QCD
2005
The compatibility between the QCD analytic invariant charge and chiral symmetry breaking is examined in detail. The coupling in question incorporates asymptotic freedom and infrared enhancement into a single expression, and contains only one adjustable parameter with dimension of mass. When inserted into the standard form of the quark gap-equation it gives rise to solutions displaying singular confining behavior at the origin. By relating these solutions to the pion decay constant, a rough estimate of about 880 MeV is obtained for the aforementioned mass-scale.
Weak kaon production off the nucleon
2010
The weak kaon production off the nucleon induced by neutrinos is studied at the low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments. This process is also potentially important for the analysis of proton decay experiments. We develop a microscopical model based on the SU(3) chiral Lagrangians. The basic parameters of the model are f pi, the pion decay constant, Cabibbo's angle, the proton and neutron magnetic moments, and the axial vector coupling constants for the baryons octet, D and F, that are obtained from the analysis of the semileptonic decays of neutron and hyperons. The studied mechanisms are the main source of kaon production for n…