Related papers: On impact parameter dependence of low-x structure …
Some novel aspects of spin studies at RHIC are summarized along with the persistent problems. Among them are those which emphasize the role of angular orbital momentum in the spin structure of the constituent quarks.
There has recently been surprising progress in understanding the spin and flavor dependence of deep inelastic structure functions in terms of the same physics needed in the simple quark models used for hadronic spectroscopy. However, the…
A model proton wave function, constructed using Poincare invariance, and constrained by recent electromagnetic form factor data, is used to study the shape of the proton. Spin-dependent quark densities are defined as matrix elements of…
In the quantum statistical parton distributions approach proposed more than one decade ago to describe the parton structure, new properties are now understood, in particular, the relation between quarks and antiquarks which leads to very…
We discuss a few examples of structure functions for polarized, semi-inclusive scattering processes to show the richness of structure. Then we indicate how polarization and particle production can be used to study the quark and gluon…
There are polarized structure functions $b_{1-4}$ for the spin-1 deuteron. We calculated the leading-twist tensor structure function $b_1$ by using convolution description for the deuteron. We found large differences between our theoretical…
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…
We analyze polarized Compton scattering which provides information on the spin-structure of the nucleon. For scattering processes with photon energies up to 100 MeV the spin-structure dependence can be encoded into four independent…
The spin dependent structure functions, g$_{1p}$ of the proton and g$_{1n}$ of the neutron, calculated in the nucleon rest frame using a relativistic quark model wave function, are compared with recent experiments.
The alternative to the standard formulation of QPM in the infinite momentum frame is suggested. The proposed approach does not require any extra assumptions in addition, consistently takes into account the parton transversal momenta and…
A review on the theoretical aspects and the experimental results of polarized deep inelastic scattering and of other hard scattering processes is presented. The following items are discussed: longitudinally polarized structure functions,…
Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. $\Lambda_b$ ,…
We derive new positivity constraints on the spin-dependent structure functions of the nucleon. These model independent results reduce conside\-rably their domain of allowed values, in particular for the chiral-odd parton distribution $h_1…
We discuss perturbative evolution of the polarized structure function g_1 in the (x,Q^2) plane, with special regard to the small-x region. We determine g_1 in terms of polarized quark and gluon distributions using coefficient functions to…
When more than one hadron takes part in a hard process, an extended set of quark distribution and fragmentation functions becomes relevant. In this talk, the derivation of Soffer-like bounds for these functions, in the case of a spin-1/2…
The orbital magnetic moment is usually associated with the relativistic spin-orbit interaction, but recently it has been shown that noncollinear magnetic structures can also be its driving force. This is important not only for magnetic…
Using contact dynamics simulations, we compare the effect of rolling resistance at the contacts in granular systems composed of disks with the effect of angularity in granular systems composed of regular polygonal particles. In simple shear…
Since the x dependence of the axial-anomaly effect in inclusive polarized deep inelastic scattering is fixed, the transformation from the $\bar{MS}$ scheme to different factorization schemes are not arbitrary. If the quark spin distribution…
The causal structure of a unitary transformation is the set of relations of possible influence between any input subsystem and any output subsystem. We study whether such causal structure can be understood in terms of compositional…
The impact-parameter representation of the spin-flip amplitude of hadron elastic scattering is examined in different unitarisation schemes, taking the Born term of the spin-flip amplitude from the Dubna Dynamical Model (DDM). It is shown…