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Edson O. da Silva

Publications and source records attributed to Edson O. da Silva.

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Electromagnetic Structure of the Pion

In this work, we analyze the electromagnetic structure of the pion. We calculate its electromagnetic radius and electromagnetic form factor in low and intermediate momentum range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion within the formalism of light-front field theory. In particular, we consider a nonsymmetrical vertex in this model, with which we calculate the electromagnetic form factor of the pion in an optimized way, so that we obtain a value closer to the experimental charge radius of the pion. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.

hep-ph

The Electromagnetic Form Factor of the Kaon in the Light-Front Approach

The kaon electromagnetic form factor is calculated within a light-front constituent quark model (LFCQM). The electromagnetic components of the current are extracted from the Feynman triangle diagram within the light-front approach. We also obtain the electroweak decay constant and the charge radius for the kaon in the light-front approach. In this work, the kaon observables are calculated and a fairly good agreement is obtained with a very higher accuracy when compared with the experimental data.

hep-ph

Pion and kaon elastic form factors in a refined light-front model

Within the framework of light-front field theory, we reassess the electromagnetic form factors of the pion and kaon. Comparison with experiment is made for the full range of momentum transfer, q^2<0, including recent data. The light-front model's single regulator mass, m_R, of the \bar qq bound-state vertex function is initially adjusted to reproduce the weak decay constants, f_π and f_K, and both meson's charge radii, r_π and r_K. We study the behavior of these observables under variation of the quark masses and find an optimized parameter set, m_u=m_d, m_s and m_R, for which they are in sensibly better agreement with experiment than in a previous analysis; a feature also observed for the elastic form factors, in particular at small q^2. This model refinement is important in view of an extension to vector and heavy-light mesons.

nucl-th