Generalized parton distributions from form factors
  The electromagnetic nucleon form factors provide constraints on generalized quark distributions. Key results of the study presented here are a strong dependence of the average impact parameter of quarks on their longitudinal momentum fraction, a striking difference in the t dependence of u and d quark contributions to elastic form factors, and an estimate of the orbital angular momentum carried by valence quarks in the nucleon. 
M. Diehl