We discuss the links between generalized parton distributions (GPDs) and elastic nucleon form factors. These links, in the form of sum rules, represent powerful constraints on parametrizations of GPDs. A Regge parametrization for GPDs at small momentum transfer, is extended to the large momentum transfer region and it is found to describe the basic features of proton and neutron electromagnetic form factor data. This parametrization is used to estimate the quark contribution to the nucleon spin

In view of the numerous experimental results recently released, we provide in this paper an update on the performance of our simple Regge model for strangeness electroproduction on the nucleon. Without refitting any parameters, a decent description of all measured observables and channels is achieved. We also give predictions for spin transfer observables, recently measured at Jefferson Lab, which have high sensitivity to discriminate between different theoretical approaches.

We have measured the nuclear transparency of the incoherent diffractive A(e,e' rho(0)) process in C-12 and Fe-56 targets relative to H-2 using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced rho(0,)s on a nucleus relative to deuterium, which is sensitive to rho A interaction, was studied as function of the coherence length (l(c)), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q(2)). While the transparency for both C-12 and Fe-56 showed no lc dependence, a significant Q(2) dependence was measured, which is consistent with calculations that included the color transparency effects. (C) 2012 Elsevier B.V. All rights reserved.

We report on the first measurement of the differential cross section of phi-meson photoproduction for the d(gamma, pK(+)K(-))n exclusive reaction channel. The experiment was performed using a tagged-photon beam and the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. A combined analysis using data from the d(gamma, pK(+)K(-))n channel and those from a previous publication on coherent phi production on the deuteron has been carried out to extract the phi - N total cross section, sigma(phi N). The extracted phi - N total cross section favors a value above 20 mb. This value is larger than the value extracted using vector-meson dominance models for phi photoproduction on the proton. (C) 2009 Elsevier B.V. All rights reserved.

The Sigma beam asymmetry in the photoproduction of neutral pions from quasi-free nucleons in a deuteron target was measured for the first time between 0.60 and 1.50 GeV, with the GRAAL polarized and tagged photon beam. The asymmetry values from the quasi-free proton were found equal to the ones extracted from a pure proton target. The asymmetries from quasi-free proton and quasi-free neutron were found equal up to 0.82 GeV and substantially different at higher energies. The results are compared with recent partial-wave analyses.

The influence of cold nuclear matter on lepto-production of hadrons in semi-inclusive deep inelastic scattering is measured using the CLAS detector in Hall B at Jefferson Lab and a 5.014 GeV electron beam. We report the K(s)(0) multiplicity ratios for targets of C, Fe, and Pb relative to deuterium as a function of the fractional virtual photon energy z transferred to the K(s)(0) and the transverse momentum squared p(T)(2). of the K(s)(0). We find that the multiplicity ratios for K(s)(0) are reduced in the nuclear medium at high z and low p(T)(2), with a trend for the K(s)(0) momentum to be broadened in the nucleus for large p(T)(2). (C) 2011 Elsevier B.V. All rights reserved.

The static polarization of HD samples has been achieved using "brute force", for HD samples purified by double distillation. Proton polarization in excess of 60% and deuteron vector polarization higher than 14% have been reached. It has been demonstrated that the ageing technique allows to get relaxation times at 1.5 K and 1 T larger than a week. It is advocated that the conventional dynamic polarization of HD should be feasible for the proton and the deuteron contained in the HD molecule. This would simplify considerably the machinery presently necessary to perform nuclear physics experiments with HD targets polarized by the static method

We have developed a fitting code based on the leading-twist handbag Deep Virtual Compton Scattering (DVCS) amplitude in order to extract Generalized Parton Distribution (GPD) information from DVCS observables in the valence region. In a first stage, with simulations and pseudo-data, we show that the full GPD information can be recovered from experimental data if enough observables are measured. If only some of these observables are measured, valuable information can still be extracted, with certain observables being particularly sensitive to certain GPDs. In a second stage, we make a practical application of this code to the recent DVCS Jefferson Lab Hall-A data from which we can extract numerical constraints for the two H GPD Compton form factors.

The result of a feasibility study to measure the Lambda polarization in associated K +-Lambda electro-production is presented. This measurement was performed in the experimental Hall C at Jefferson Lab. The scattered electron was detected in the HMS spectrometer, and the electro-produced kaon and the proton from the Lambdararrppi - decay were both detected in the SOS spectrometer. This quantity is very sensitive to the elementary p(e,e'K)Lambda process and gives information on resonance production, and Regge exchange, among others. The result presented was measured at Q 2=1.50 (GeV/c) 2 and costhetas KgammaCM=14deg. The limits of the Lambda polarization, with respect to the p gammatimesp K axis, were found to be -0.21 and +0.89 with a confidence level of 68%. The result is compared to theoretical predictions based on an effective hadronic field Lagrangian model and a Regge framework model

The ep -> e'pp(0) reaction has been measured using the 5.754 GeV electron beam of Jefferson Lab and the CLAS detector. This represents the largest ever set of data for this reaction in the valence region. Integrated and differential cross-sections are presented. The W, Q(2) and t dependences of the cross-section are compared to theoretical calculations based on the t-channel meson-exchange Regge theory, on the one hand, and on quark handbag diagrams related to Generalized Parton Distributions (GPDs) on the other hand. The Regge approach can describe at the approximate to 30% level most of the features of the present data while the two GPD calculations that are presented in this article which succesfully reproduce the high-energy data strongly underestimate the present data. The question is then raised whether this discrepancy originates from an incomplete or inexact way of modelling the GPDs or the associated hard scattering amplitude or whether the GPD formalism is simply inapplicable in this region due to higher-twists contributions, incalculable at present.

Recent realistic simulations confirm that the polarization of the fuel would improve significantly the DT fusion efficiency. We have proposed an experiment to test the persistence of the polarization in a fusion process, using a terawatt laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse producing a He-3 and a neutron in the final state. The angular distribution of the neutrons and the change in the corresponding total cross section are related to the polarization persistence. The experimental polarization of DT fuel is a technological challenge. Possible paths for Magnetic Confinement Fusion (MCF) and for Inertial Confinement Fusion (ICF) are reviewed. For MCF, polarized gas can be used. For ICF, cryogenic targets are required. We consider both, the polarization of gas and the polarization of solid DT, emphasizing the Dynamic Nuclear polarization (DNP) of HD and DT molecules.

Beam asymmetry and differential cross-section for the reaction gamma p -> eta p were measured from production threshold to 1500MeV photon laboratory energy. The two dominant neutral decay modes of the eta-meson, eta -> 2 gamma and eta -> 3 pi(0) , were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.