Poincaré covariant quark models of the the nucleon, the ∆ resonance and their excitations are explored. The baryon states are represented by eigenfunctions of the four-velocity and a confining mass operator, which reproduces the empirical spectrum up to ∼ 1700 MeV to an accuracy of ∼ 6%. Models of constituent quark currents provide the relations between ground-state properties and transition am...

I report the current status of the heavy-light decay constants, the bag parameters and the semileptonic form factors. I compare the heavy-light decay constants with Wilson-Wilson and clover-clover fermions. Systematic errors such as scale setting and renormalization factors are also discussed. 1/M dependences for the heavy-light semi-leptonic form factors near q = q m ax with clover-clover and ...

Preliminary results of a calculation of disconnected nucleon electromagnetic factors factors on the lattice are presented. The implementation of the numerical subtraction scheme is outlined. A comparison of results for electric and magnetic disconnected form factors on two lattice sizes with those of the Kentucky group is presented. Unlike previous results, the results found in this calculation...

The determination of light hadron physics properties is of considerable interest to experimental labs such as Jefferson Lab. Many quantities, such as hadron form-factors and generalized structure functions, are not well understood theoretically. The available and forthcoming high precision experimental data presents considerable challenges and many opportunities for corresponding lattice calcul...

Elastic electromagnetic nucleon form factors have long provided vital information about the structure and composition of these most basic elements of nuclear physics. The form factors are a measurable and physical manifestation of the nature of the nucleons’ constituents and the dynamics that binds them together. Accurate form factor data obtained in recent years using modern experimental facil...

The pion electromagnetic form factor is often considered a good observable for studying the relative accuracy of perturbative and nonperturbative descriptions of QCD as the energy scale varies. It is hoped that because the pion is the lightest and simplest hadron that perturbative descriptions will remain accurate at lower energy scales than predictions for heavier and more complicated hadrons,...

There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at MIT-Bates...

The theory of the on-shell Sudakov form factor to all order of logarithms is explained.

Measurements of the electric and magnetic form factors have been carried out by means of scattering of polarized electrons from vector-polarized hydrogen and deuterium. The experiment used the longitudinally polarized stored electron beam of the MIT-Bates South Hall Ring along with an isotopically pure, highly vector-polarized internal atomic hydrogen and deuterium target provided by an atomic ...

While radiative corrections of infrared origin normally depress high energy amplitudes (Sudakov form factors), we find that in some cases resummation of leading effects produces exponentials with positive exponents, giving rise to amplitudes that grow indefinitely with energy. The effect happens in broken gauge theories like the electroweak sector of the Standard Model, and is related to the ex...