Light-front quark distributions in the nucleon and nucleon electromagnetic form factors

Longitudinal and transverse quark momentum distributions in the nucleon are calculated from a phenomenological quark-nucleon vertex function obtained through an investigation of the nucleon electromagnetic form factors within a light-front framework.Comment: 6 pages, 11 figs. proceedings of LC2009, to appear in Nucl. Phys.

Relativistic dynamics of Qqq systems

The bound state of constituent quarks forming a $Qqq$ composite baryon is investigated in a QCD-inspired effective light-front model. The light-front Faddeev equations are derived and solved numerically. The masses of the spin 1/2 low-lying states of the nucleon, $\Lambda^0$, $\Lambda^+_c$ and $\Lambda^0_b$ are found and compared to the experimental data. The data is qualitatively described with a flavor independent effective interaction.Comment: 18 pages, include 6 figures, 2 eps figures, use latex, revtex. To appear Phys. Rev D (2002

Ground State Masses and Biding Energies of the Nucleon, Hyperon and Heavy Baryons in a Light-Front Model

The ground state masses and binding energies of the nucleon, $\Lambda^0$, $\Lambda^+_c$, $\Lambda^0_b$ are studied within a constituent quark QCD-inspired light-front model. The light-front Faddeev equations for the $Qqq$ composite spin 1/2 baryons, are derived and solved numerically. The experimental data for the masses are qualitatively described by a flavor independent effective interaction.Comment: 13 pages, include 4 eps figures, use latex, revte

The pion electromagnetic form-factor in a QCD-inspired model

We present detailed numerical results for the pion space-like electromagnetic form factor obtained within a recently proposed model of the pion electromagnetic current in a confining light-front QCD-inspired model. The model incorporates the vector meson dominance mechanism at the quark level, where the dressed photon with $q^+>0$ decay in an interacting quark-antiquark pair,wich absorbs the initial pion and produces the pion in the final state.Comment: Talk given in Light-Cone 2004, Amsterdam,NL., 16-20 August, 2004. To appear in "Few-Body Systems". 4 pages, 2 figues eps, use Few-Body Sytems latex styl

Timelike and spacelike hadron form factors, Fock state components and light-front dynamics

A unified description of spacelike and timelike hadron form factors within a light-front model was successfully applied to the pion. The model is extended to the nucleon to study the role of $q \bar q$ pair production and of nonvalence components in the nucleon form factors. Preliminary results in the spacelike range $0 \le Q^2 \le 10 ~ (GeV/c)^2$ are presented.Comment: 4 pages, espcrc1.sty. proceedings of FB XVIII (August 2006, Brazil), to be published in Nucl. Phys.

Electromagnetic Hadron Form Factors and Higher Fock Components

Investigation of the spacelike and timelike electromagnetic form factors of hadrons, within a relativistic microscopical model characterized by a small set of hypothesis, could shed light on the components of hadron states beyond the valence one. Our relativistic approach has been successfully applied first to the pion and then the extension to the nucleon has been undertaken. The pion case is shortly reviewed as an illustrative example for introducing the main ingredients of our approach, and preliminary results for the nucleon in the spacelike range $-10 (GeV/c)^2\le q^2 \le 0$ are evaluated.Comment: 8 pages, 6 figs, espcrc1.sty included. Proceedings of Fifth International Conference on Perspectives In Hadronic Physics, ICTP, May 22-26, 200

Electromagnetic form factors of the nucleon in spacelike and timelike regions

An approach for a unified description of the nucleon electromagnetic form factors in spacelike and timelike regions is presented. The main ingredients of our model are: $i)$ a Mandelstam formula for the matrix elements of the nucleon electromagnetic current; $ii)$ a 3-dimensional reduction of the problem on the Light-Front performed within the so-called {\tt Propagator Pole Approximation} ({\bf PPA}), which consists in disregarding the analytical structure of the Bethe-Salpeter amplitudes and of the quark-photon vertex function in the integration over the minus components of the quark momenta; $iii)$ a dressed photon vertex in the $q\bar{q}$ channel, where the photon is described by its spin-1, hadronic component.Comment: 8 pages, 9 figs., macro added. Proceedings of the XI Conf. on Problems in Theoretical Nuclear Physics, Cortona, Oct. 11-14, 200

Electromagnetic form factor of the pion in the space- and time-like regions within the front-form dynamics

The pion electromagnetic form factor is calculated in the space- and time-like regions from -10 $(GeV/c)^2$ up to 10 $(GeV/c)^2$, within a front-form model. The dressed photon vertex where a photon decays in a quark-antiquark pair is depicted generalizing the vector meson dominance ansatz, by means of the vector meson vertex functions. An important feature of our model is the description of the on-mass-shell vertex functions in the valence sector, for the pion and the vector mesons, through the front-form wave functions obtained within a realistic quark model. The theoretical results show an excellent agreement with the data in the space-like region, while in the time-like region the description is quite encouraging.Comment: 9 pages + 4 figures. To appear in Phys. Lett.