Generalized Parton Distributions and Generalized Distribution Amplitudes : New Tools for Hadronic Physics

The generalized parton distributions and the generalized distribution amplitudes give access to a deeper understanding of the quark and gluon content of hadrons. In this short review, we select some new developments of their interesting connections with the physics information that one can extract from exclusive reactions at medium and high energies.Comment: 4 pages, Talk given at the International Conference on Theoretical Physics, TH2002, Paris, July 200

The nucleon's transversity and the photon's distribution amplitude probed in lepton pair photoproduction

We describe a new way to access the chiral odd transversity parton distribution in the proton through the photoproduction of lepton pairs on transversely polarized target. The basic ingredient is the interference of the Bethe Heitler or Drell-Yan amplitudes with the amplitude of a process, where the photon couples to quarks through its twist-2 chiral-odd distribution amplitude. This approach permits to scan experimentally the shape of the transversity distribution in a nucleon as well as the photon distribution amplitude.Comment: 4 pages, proceedings of the ICHEP conference, Paris july 201

Neutrino-production of a charmed meson and the transverse spin structure of the nucleon

We calculate the amplitude for exclusive neutrino production of a charmed meson on an unpolarized target, in the colinear QCD approach where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We demonstrate that the transversity chiral odd GPDs contribute to the transverse cross section if the hard amplitude is calculated up to order mc/Q. We show how to access these GPDs through the azimuthal dependence of the nu N -> mu D N differential cross section.Comment: 5 pages, 1 figure. Version 2 adds a few clarifications and references. As published in Physical Review Letters 115, 092001 (2015

Deeply Virtual Compton Scattering on the Deuteron

We study deeply virtual Compton scattering (DVCS) on a deuteron target. We model the Generalized Quark Distributions in the deuteron by using the impulse approximation for the lowest Fock-space state. Numerical predictions are given for the unpolarized cross sections for the kinematical regimes relevant for JLab and HERMES at HERA. Differential cross sections show the same pattern as for the proton case and at low values of t they are of comparable size.Comment: 6 pages, 4 eps figures. Contribution to the European Workshop on the QCD Structure of the Nucleon (QCD-N'02), Ferrara, Italy, 3-6 Apr 200