Constraints on the H~\tilde{H} Generalized Parton Distribution from Deep Virtual Compton Scattering Measured at HERMES

We have analyzed the longitudinally polarized proton target asymmetry data of the Deep Virtual Compton process recently published by the HERMES collaboration in terms of Generalized Parton Distributions. We have fitted these new data in a largely model-independent fashion and the procedure results in numerical constraints on the $\tilde{H}_\mathrm{Im}$ Compton Form Factor. We present its $t-$ and $\xi-$ dependencies. We also find improvement on the determination of two other Compton Form Factors, $H_\mathrm{Re}$ and $H_\mathrm{Im}$.Comment: 14 pages, 5 figure

Extraction of Compton Form Factors from DVCS data

We present the results of a fitter code which aims at extracting Compton Form Factors (CFFs) from DVCS (Deep Virtual Compton Scattering) experimental data, in a largely model-independent way. CFFs are linked to GPDs (Generalized parton Distributions) and are the quantities which are directly measurable. The data that we have analyzed are from JLab and HERMES experiments. We obtain some first important constraints on the $H$ and $\tilde{H}$ CFFs. The kinematical dependences ($x_B$, $t$) of these CFFs provide some new insights on nucleon structure.Comment: 5 pages, 1 figure. Proceeding of ICHEP10 conference, July 22-28, 201

Generalized Parton Distributions : Experimental aspects

After briefly outlining the formalism of the Generalized Parton Distributions (GPDs) in the first sections, we discuss some general considerations for their experimental study : in particular, the relation between GPDs and experimental observables and the need and requirements for a dedicated experimental facility. Also, we review and comment the first experimental signatures of this physics recently observed by the HERMES and CLAS (at JLab) collaborations.Comment: 10 pages, Invited talk at ICTP 3rd International Conference on Perspectives in Hadronic Physics, Trieste, Italy, 7-11 May 2001. Submitted to Nucl.Phys.

Generalized Parton Distributions from Deep Virtual Compton Scattering at CLAS

We have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factors $H_{Im}$ and $\tilde{H}_{Im}$ with uncertainties, in average, of the order of 30%.Comment: 9 pages, 5 figure

Deeply pseudoscalar meson electroproduction with CLAS and Generalized Parton Distributions

We discuss the recent data of exclusive $\pi^0$ (and $\pi^+$) electroproduction on the proton obtained by the CLAS collaboration at Jefferson Lab. It is observed that the cross sections, which have been decomposed in $\sigma_T +\epsilon\sigma_L$, $\sigma_{TT}$ and $\sigma_{LT}$ structure functions, are dominated by transverse amplitude contributions. The data can be interpreted in the Generalized Parton Distribution formalism provided that one includes helicity-flip transversity GPDs.Comment: 4 pages, 2 figures PANIC14 conference proceedin

Deeply Virtual Electroproduction of Photons and Mesons

In this paper, after a brief summary of the properties of the Off-Forward Parton Distributions, we give some examples of what could be the experimental opportunities to access them at the current high-energy lepton facilities : JLab (E_e >= 6 GeV), HERMES (E_e = 27 GeV) and COMPASS (E_mu = 200 GeV).Comment: 5 pages, 3 figure

Timelike Compton Scattering off the Proton: beam and/or target spin asymmetries

We present a sample of results of our work to be published soon on Timelike Compton scattering off the proton, in the framework of the Generalized Parton Distributions formalism.Comment: 2 figures, 4 pages, PANIC 2014 conference proceedin