Related papers: Quark Distribution Functions in a Diquark Spectato…
The electromagnetic excitation of the nucleon resonances is studied in the framework of Constituent Quark Models. Particular attention is devoted to the transition to the $\Delta$ resonance and to the issue of a possible deformation of…
The recent measurements of azimuthal single spin asymmetries by the HERMES collaboration has opened up new possibility to measure chiral-odd distribution functions through semi-inclusive deep-inelastic scatterings. Here, predictions are…
We study the transverse momentum dependent quark-gluon-quark correlation function. Using a spectator diquark model, we calculate the eight time-reversal-odd interaction-dependent twist-3 quark distributions appearing in the decomposition of…
We study the chiral-odd transversity spin-dependent quark distribution function $h_1 (x)$ of the nucleon in a constituent quark model. The twist-2 structure functions, $f_1(x)$, $g_1(x)$ and $h_1(x)$ are calculated within the diquark…
At large N_c the nucleon can be viewed as a soliton of the effective chiral lagrangian. This picture of nucleons allows a consistent nonperturbative calculation of the leading-twist parton distributions at a low normalization point. We…
We suggest a method of constructing gauge invariant quark and gluon distributions that describe an abstract QCD observable and apply this method to analyze angular momentum of a hadron. In addition to the known quark and gluon polarized…
We use a spectator framework to investigate the spectral properties of quark-quark-gluon correlators and use this to study gluonic pole matrix elements. Such matrix elements appear in principle both for distribution functions such as the…
We suggest a duality between the statistical and standard (dynamical) distributions of partons in the nucleons. The temperature parameter entering into the statistical form for the quark distributions is estimated. It is found that this…
Modern analyses of diffusion processes have proposed nonlinear versions of the Fokker-Planck equation to account for non-classical diffusion. These nonlinear equations are usually constructed on a phenomenological basis. Here we introduce a…
The one-particle momentum transfer operator is derived in point-form spectator approximation for $NN$ system. General expression is applied to elastic electron-deuteron scattering and to deuteron photodisintegration.
We develop a formalism to evaluate the Sivers function. The approach is well suited for calculations which use constituent quark models to describe the structure of the nucleon. A non-relativistic reduction of the scheme is performed and…
Rescattering of the struck quark in Deep Inelastic Scattering implies that measured parton distributions are not directly related to the Fock state probabilities of the target wave function. The production amplitudes acquire dynamical…
We present a quark-quark interaction for the complete study of the meson spectra, from the light to the heavy sector. We compare the quark model predictions against well-established $q\bar q$ experimental data. This allows to identify…
We find a closed-form for the distribution function (defined in terms of a Wigner operator) for hot coloured particles in a background gluon field, in the hard thermal loop approximation. We verify that the current is the same as that…
The pion structure function is investigated in a simple model, where pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi-> gamma* pi scattering amplitude is…
Model studies play an important role for the understanding and elucidation of the nonperturbative properties of transverse momentum dependent parton distribution functions (TMDs). The parton model is often a helpful framework and starting…
Quark-hadron duality is studied in a systematic way for both the unpolarized and polarized structure functions, by taking into account all the available data in the resonance region.In both cases, a detailed perturbative QCD based analysis…
The fragmentation of a colored parton directly into a pair of colorless hadrons is a non-perturbative mechanism that offers important insights into the nucleon structure. Di-hadron fragmentation functions can be extracted from…
We introduce the concept of the nucleon energy correlators, a set of novel objects that encode the microscopic details of a nucleon, such as the parton angular distribution in a nucleon, the collinear splitting to all orders, as well as the…
A brief overview of various problems related to the description of a polarized proton in quark models is presented. Structure functions are discussed both for longitudinal and transverse polarization. A recently introduced quantity,…