Related papers: Parton Distribution within Virtual Particles and $…
Using constituent quark model constraints we calculate the gluon and sea-quark content of pions solely in terms of their valence density (fixed by \pi N Drell-Yan data) and the known sea and gluon distributions of the nucleon, using the…
This article gives an overview over recent results on quark and gluon helicity distributions obtained in deep inelastic lepton nucleon scattering and proton proton interactions. Future experimental programs to study the nucleon structure…
At high energies a form of fragmentation function for a heavy quark into a hadron is substantiated to agree with a reciprocity relation to the distribution of heavy quark as the virtual parton in the hadron. The relevance of the relation is…
We give an overview of low-energy Compton scattering (gamma^(*) p --> gamma p) with a real or virtual incoming photon. These processes allow the investigation of one of the fundamental properties of the nucleon, i.e. how its internal…
We possess convincing experimental evidence for the fact that the real photon has non-trivial parton structure. On the other hand, interactions of the cosmic microwave background photons with high energy particles propagating through the…
A dispersion relation formalism for the virtual Compton scattering (VCS) reaction on the proton is presented, which for the first time allows a dispersive evaluation of 4 generalized polarizabilities at a four-momentum transfer $Q^2 \leq$…
Spin and transverse momentum dependent parton distributions - Generalized Parton Distributions (GPDs) - are at the interface between the QCD structure of the hadrons and observable quantities. The GPDs are linear superpositions within…
Recently, there have been some interesting developments involving off-forward parton distributions of the nucleon, deeply virtual Compton scattering, and hard diffractive vector-meson production. These developments are triggered by the…
Access to Generalised Parton Distributions (GPDs) through Deeply Virtual Compton Scattering (DVCS) is briefly described. Presently available experimental results on DVCS are summarized in conjunction with plans for future measurements.
Virtual Compton Scattering off the proton: gamma* p to gamma p, is a new field of investigation of nucleon structure. Several dedicated experiments have been performed at low c.m. energy and various momentum transfers, yielding specific…
The description of longitudinal photons is far from trivial, and their phenomenological importance is largely unknown. While the cross section for direct interactions is calculable, an even more important contribution could come from…
A new model for the exchange of two gluons between the virtual photon and the proton, in non-diffractive deeply inelastic electron-proton scattering, is developed and studied. This model relies on a perturbative calculation, previously…
We present a method which allows to extract theoretical informations out of a limited set of experimental data and observables, forming up in general an under- constrained system. It has been applied to the field of nucleon structure, in…
Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when the target and/or quark is transversely polarized. In combination with the final state…
A simple picture of the constituent quark as a composite system of point-like partons is used to construct the unpolarized and polarized parton distributions by a convolution between constituent quark momentum distributions and constituent…
We discuss the general formalism for the calculation in light-cone quark models of the fully unintegrated, off-diagonal quark-quark correlator of the nucleon. The corresponding distributions in impact parameter space are the Wigner or…
Different theoretical methods used for the description of diffractive processes in small-x deep inelastic scattering are reviewed. The semiclassical approach, where a partonic fluctuation of the incoming virtual photon scatters off a…
A non-perturbative approach to Generalized Parton Distributions, and to Deeply Virtual Compton Scattering in particular, based on off mass shell extension of dual amplitudes with Mandelstam analyticity (DAMA) is developed with the spin and…
We discuss recent theoretical results on diffractive deeply inelastic scattering, focusing on the partonic picture of diffraction in configuration space and the predictions for the beta behavior and the scaling violation.
At a low resolution scale with $Q^2={\mu}^2$ corresponding to the nucleon bound state; deep inelastic unpolarized structure functions $F_1(x,{\mu}^2)$ and $F_2(x,{\mu}^2)$ are derived with correct support using the symmetric part of the…