Generalized parton distributions from hadronic observables: Zero skewness

We propose a physically motivated parametrization for the unpolarized generalized parton distributions. At zero value of the skewness variable, zeta, the parametrization is constrained by simultaneously fitting the experimental data on both the nucleon elastic form factors and the deep inelastic structure functions. A rich phenomenology can be addressed based on this parametrization. In particular, we track the behavior of the average: (i) interparton distances as a function of the momentum fraction, X, (ii) X as a function of the four-momentum transfer, t; and (iii) the intrinsic transverse momentum k(perpendicular to) as a function of X. We discuss the extension of our parametrization to zeta not equal 0 where additional constraints are provided by higher moments of the generalized parton distributions obtained from ab initio lattice QCD calculations.