Galactic Nonlinear Dynamic Model

We develop a model for spiral galaxies based on a nonlinear realization of the Newtonian dynamics starting from the momentum and mass conservations in the phase space. The radial solution exhibits a rotation curve in qualitative accordance with the observational data.Comment: 6 pages, 1 figure. Talk given in the 7th Alexander Friedmann International Seminar, June 29 to July 5, 2008, Joao Pessoa, PB, Brazi

Electromagnetic structure and weak decay of pseudoscalar mesons in a light-front QCD-inspired model

We study the scaling of the $^3S_1-^1S_0$ meson mass splitting and the pseudoscalar weak decay constants with the mass of the meson, as seen in the available experimental data. We use an effective light-front QCD-inspired dynamical model regulated at short-distances to describe the valence component of the pseudoscalar mesons. The experimentally known values of the mass splittings, decay constants (from global lattice-QCD averages) and the pion charge form factor up to 4 [GeV/c]$^2$ are reasonably described by the modelComment: 27 Pages, 7 eps figures,use revtex

Weak decay constant of pseudscalar meson in a QCD-inspired model

We show that a linear scaling between the weak decay constants of pseudoscalar and the vector mesons masses is supported by the available experimental data. The decay constant scale as $f_m/f_{pi}=M_V/M_{\rho}$ (f_m is decay constant and M_V vector meson ground state mass). This simple form is justified within a renormalized light-front QCD-inpired model for quark-antiquark bound states.Comment: 4 pages, use revtex style. To appear "Brazilian Journal of Physics (2003)

Why pair production cures covariance in the light-front?

We show that the light-front vaccum is not trivial, and the Fock space for positive energy quanta solutions is not complete. As an example of this non triviality we have calculated the electromagnetic current for scalar bosons in the background field method were the covariance is restored through considering the complete Fock space of solutions. We also show thus that the method of "dislocating the integration pole" is nothing more than a particular case of this, so that such an "ad hoc" prescription can be dispensed altogether if we deal with the whole Fock space. In this work we construct the electromagnetic current operator for a system composed of two free bosons. The technique employed to deduce these operators is through the definition of global propagators in the light front when a background electromagnetic field acts on one of the particles.Comment: 11 pages, 2 figure

Associação micorrízica em plantas nativas da caatinga: ocorrência e eficiência simbiótica para produção de mudas.

O objetivo deste trabalho foi ampliar os conhecimentos sobre a associação micorrizica (número de glomerosporos, potencial de infectividade do solo, percentual de colonização e diversidade de FMA) em plantas nativas da caatinga, assim como avaliar o efeito do regime hídrico sobre a reprodução desses fungos

Resposta de plantas forrageiras à inoculação com fungos micorrízicos arbusculares (FMA) e bactérias fixadoras de nitrogênio (FBN): simbiose e eficiência no crescimento vegetal sob condições semi-áridas.

O presente trabalho teve por objetivos avaliar a condição micorrízica no campo das variedades Petrolina e Forrageiro de Cajanus cajan e a eficiência da inoculação com fungos micorrízicos arbusculares (FMA) e BFN no crescimento dessa forrageira em dois tipos de solo