Flexible parametrization of generalized parton distributions from deeply virtual Compton scattering observables

Abstract

We present a physically motivated parametrization of the chiral-even generalized parton distributions in the non-singlet sector obtained from a global analysis using a set of available experimental data. Our analysis is valid in the kinematical region of intermediate Bjorken x and for Q 2 in the multi-GeV region which is accessible at present and currently planned facilities. Relevant data included in our fit are from the nucleon elastic form factors measurements, and from deep inelastic scattering experiments. Additional information provided by lattice calculations of the higher moments of generalized parton distributions, is also considered. Recently extracted observables from Deeply Virtual Compton Scattering on the nucleon are reproduced by our fit.

Interpretation of the flavor dependence of nucleon form factors in a generalized parton distribution model

“…[13] where using a reggeized quark diquark model we provided a quantitative fit the proton's and neutron's electroweak form factors. The large number of parameters that is necessary to fit GPDs was handled by using a recursive procedure.…”

“…[13,19,20] we developed a quark diquark model with the aim of interpreting DVCS data. The basic structures of the model are the helicity quark-proton scattering amplitudes at leading order with proton-quarkdiquark vertices (Fig.2).…”

Angular momentum sum rule for spin-one hadronic systems

“…Both the unpolarized and polarized u and d quarks GPDs used in the calculation are from the parametrization of Ref. [14]. The importance of perturbative QCD evolution is evident from the comparison of results at an initial low scale used e.g.…”

“…where A λ N λ q ;λ N ,λq and B λ ,λ N ;λ,λ N , are the quarknucleon [14], and nucleon-deuteron helicity amplitudes, respectively, Λ, λ N , λ q , being the deuteron, nucleon, and quark helicities. H 2 can be explicitly evaluated from Eq.…”

“…All curves were calculated at the scale Q 2 = 4 GeV 2 , using the parametrization from Ref. [14] for the free nucleon. (Lower panel) Ratio of deuteron to nucleon contributions to angular momentum, H2/(HN + EN ) ≡ JD(x)/JN (x), (full curve), calculated using Eq.…”