The feasibility of extracting generalized parton distributions (GPDs) from deeply virtual Compton scattering (DVCS) data has recently been questioned because the existence an infinite set so-called ``shadow GPDs'' (SGPDs). These SGPDs depend on process and manifest as multiple solutions (at a fixed scale ${Q}^{2}$) to inverse problem that needs be solved infer GPDs DVCS data. therefore pose sig...

Parton distribution functions, which represent the flavor and spin structure of the nucleon, provide invaluable information in illuminating quantum chromodynamics in the confinement region. Among various processes that measure such parton distribution functions, semi-inclusive deep inelastic scattering is regarded as one of the golden channels to access transverse momentum dependent parton dist...

In terms of multiple scattering picture, we calculate the double scattering effect in the transverse momentum distribution of J/ψ photoproduction. Applying the generalized factorization theorem, we find that the contributions from double scattering can be expressed in terms of twist-4 nuclear parton correlation functions, which is the same as that used to explain the nuclear dependence in di-je...

M.V. Polyakov Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum, Germany and Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188350, Russia Abstract We discuss a new leading-order parameterization of generalized parton distributions of the proton, which is based on the idea of duality. In its minimal version, the parameterization is defined by the usual...

Abstract. Hadron structure from high-Q2 γ∗ p scattering processes is often expressed in terms of hadronic matrix elements of nonlocal operators. Properly defining and interpreting these quantities is very important in light of experiments aiming to extract transverse momentum dependent parton distributions or generalized parton distributions. The current status will be reviewed, including recen...

Parton densities are among the most important sources of information on hadron structure at the level of quarks and gluons. The conventional densities describe the distribution of longitudinal momentum and helicity carried by partons in a fast-moving hadron. Generalized parton distributions (GPDs) complement this essentially one-dimensional picture with information on the directions transverse ...

ACCESSING THE SPACE–TIME DEVELOPMENT OF HEAVY–ION COLLISIONS WITH THEORY AND EXPERIMENT By David Alan Brown In this thesis we discuss ways to access the space-time development of heavy-ion reactions using both theory and experiment. From the theoretical side, we discuss modeling ultra-relativistic, parton-dominated, heavy-ion reactions. This discussion is broken into a discussion of transport-l...

The process of exclusive heavy vector meson photoproduction, γp → V p, is studied in the framework of QCD factorization. The mass of the produced meson, V = Υ or J/Ψ, provides a hard scale for the process. We demonstrate, that in the heavy quark limit and at the one-loop order in perturbation theory, the amplitude factorizes in a convolution of a perturbatively calculable hard-scattering amplit...

Exclusive electroproduction of a K or K * meson on the nucleon can give a Θ + pentaquark in the final state. This reaction offers an opportunity to investigate the structure of pentaquark baryons at parton level. We discuss the generalized parton distributions for the N → Θ + transition and give the leading order amplitude for electroproduction in the Bjorken regime.

We show that for both quarks and gluons there are eight generalized parton distributions in the proton: four which conserve parton helicity and four which do not. We explain why time reversal invariance does not reduce this number from eight to six, as previously assumed in the literature.