The present understanding of the spin structure of the nucleon is briefly reviewed. The main focus is on parton helicity distributions, orbital angular momentum of partons as defined through generalized parton distributions, as well as single spin asymmetries and time-reversal odd correlation functions.

The covariant parton model is generalized to describe quark correlators in a systematic way. Previous results are reproduced for the T-even leading-twist transverse momentum dependent distribution functions (TMDs), and first time all twist-3 TMDs evaluated this model. We apply approach evaluate fully unintegrated correlator which allows us understand model-specific relations between different T...

We present the general formalism required to derive generalized parton distributions within a convolution model where the bare nucleon is dressed by its virtual meson cloud. In the one-meson approximation the Fock states of the physical nucleon are expanded in a series involving a bare nucleon and two-particle, meson-baryon, states. The baryon is assumed here to be either a nucleon or a ∆ descr...

The crossing properties of the matrix elements of non-local operators, parameterized by Generalized Parton Distribution, are considered. They are especially simple in terms of the Double Distributions which are common for the various kinematical regions. As a result, Double Distributions may be in principle extracted from the combined data in these regions by making use of the inverse Radon tra...

Parton distributions play an important role in the QCD description of hard scattering processes. In particular, generalized parton distributions (GPDs) and transverse momentum dependent parton distributions (TMDs) have extensively been studied during the last decade. We focus here on the most general form of quark-quark correlation functions, the socalled generalized transverse momentum depende...

Several hard exclusive scattering processes admit a description in terms of generalized parton distributions and perturbative hard-scattering kernels. Both the physical amplitude and the hard-scattering kernels fulfill dispersion relations. We give a detailed investigation of their consistency at all orders in perturbation theory. The results shed light on the information about generalized part...

Recently there has been renewed interest on polarized parton distributions in the nucleon, largely stimulated by the development of the next-to leading order(NLO) QCD calculations of polarized parton distribution functions and acquisition of high-precision polarized data on various targets. In this work, requiring reasonable physical conditions, (1)the positivity condition and (2) the counting ...

Most high energy collisions can be described by a single hard scattering. By studying the single scattering, we can extract the parton distribution functions and test the short-distance dynamics of strong interactions. The normal parton distributions have the interpretation of the probability distributions to find a parton within a hadron. On the other hand, in order to study quantum correlatio...

Optimum nuclear parton distributions are determined by an analysis of muon and electron deep inelastic scattering data. Assuming simple A dependence and polynomial functions of x and 1−x for nuclear modification of parton distributions, we determine the initial distributions by a χ 2 analysis. Although valence-quark distributions are relatively well determined except for the small-x region, ant...