Generalized parton distributions, the hunt for quark orbital momenta

The Proceedings of SPIN2008 will be published by the American Institute of Physics (AIP) in print and electronic versions that will be identical.International audienceThe Generalized Parton Distributions (GPDs) are the appropriate framework for a universal description of the partonic structure of the nucleon. They characterize the dynamics of quarks and gluons inside the nucleon and consequently contain information about the spin of the nucleon. The current experimental knowledge about GPDs is rewieved with the emphasis on the determination of Eq(Q2,x,x , t), the least known and constrained GPD, of particular importance in the nucleon spin puzzle. The perspectives of this experimental program are also addressed