Angular momentum sum rule in nuclei

In this work we derive a sum rule for the angular momentum of a spin 1 hadronic system.Comment: 5 pages, to appear in Proceedings of XVIII International Workshop on Deep-Inelastic Scattering and Related Subjects, April 19 -23, 2010, Convitto della Calza, Firenze, Ital

Microscopic Description of Deeply Virtual Compton Scattering off Spin-0 Nuclei

We evaluate within a microscopic calculation the contributions of both coherent and incoherent deeply virtual Compton scattering from a spin-0 nucleus. The coherent contribution is obtained when the target nucleus recoils as a whole, whereas for incoherent scattering break-up configurations for the final nucleus into a an outgoing nucleon and an $A-1$ system are considered. The two processes encode different characteristics of generalized parton distributions.Comment: 7 pages, 3 figure

The impact of changing technology on the demand for air transportation

Demand models for air transportation that are sensitive to the impact of changing technology were developed. The models are responsive to potential changes in technology, and to changing economic, social, and political factors as well. In addition to anticipating the wide differences in the factors influencing the demand for long haul and short haul air travel, the models were designed to clearly distinguish among the unique features of these markets

Generalized Parton Distributions from Hadronic Observables

We propose a physically motivated parametrization for the unpolarized generalized parton distributions, H and E, valid at both zero and non-zero values of the skewness variable, \zeta. At \zeta=0, H and E are determined using constraints from simultaneous fits of experimental data on both the nucleon elastic form factors and the deep inelastic structure functions. Lattice calculations of the higher moments constrain the parametrization at \zeta > 0. Our method provides a step towards a model independent extraction of generalized distributions from the data that is alternative to the mathematical ansatz of double distributions.Comment: 4 pages, 2 figures, to appear in the proceedings of DIS 200

Angular momentum sum rule for spin one hadronic systems

We derive a sum rule for the total quark angular momentum of a spin-one hadronic system within a gauge invariant decomposition of the hadron's spin. We show that the total angular momentum can be measured through deeply virtual Compton scattering experiments using transversely polarized deuteron targets.Comment: 4 pages, 2 figures, changes in text, figures changed, references change

Nuclear Medium Modifications of Hadrons from Generalized Parton Distributions

We study the structure of generalized parton distributions in spin 0 nuclei within a microscopic approach for nuclear dynamics. GPDs can be used on one side as tools to unravel the deep inelastic transverse structure of nuclei in terms of both transverse spatial and transverse momentum degrees of freedom. On the other, one can obtain information on GPDs themselves by observing how they become modified in the nuclear environment. We derive the structure of the nuclear deeply virtual Compton scattering tensor and generalized parton distributions at leading order in $Q$ in a field-theoretical framework. The nuclear generalized parton distributions are calculated using a two step process -- the convolution approach -- where the scattering process happens from a quark inside a nucleon, itself inside a nucleus, disregarding final state interactions with both the nuclear and nucleon debris. We point out that details of the nuclear long range interactions such as two-body currents, can be disregarded compared to the deep inelastic induced modifications of the bound GPDs. We show how the pattern of nuclear modifications predicted, and in particular the deviations of off-shell effects from the longitudinal convolution provide clear signals to be sought in experimental measurements. Finally, we find interesting relationships by studying Mellin moments in nuclei: in particular we predict the $A$-dependence for the $D$-term of GPDs within a microscopic approach, and the behavior with $t$ of the total momentum carried by quarks in a nucleus. The latter provides an important element for the evaluation of nuclear hadronization phenomena which are vital for interpreting current and future data at RHIC, HERMES and Jefferson Lab.Comment: 29 pages, 10 figure