Generalized parton distributions, nucleon form factors, and large-t processes

Abstract

The connection of generalized parton distributions (GPDs) to processes at large momentum transfer (high-t), and the links between GPDs and elastic nucleon form factors are discussed here. These links, in the form of sum rules, represent powerful constraints on parametrizations of GPDs. A Regge parametrization for the GPDs at small-t, which is surprisingly observed from the chiral quark soliton model results, is extended to the large-t region and it is found to catch the basic features of proton and neutron electromagnetic form factor data. It is furthermore discussed how these GPDs at large-t enter into two-photon exchange processes and resolve the discrepancy between Rosenbluth and polarization experiments of elastic electron nucleon scattering.

Nucleon form factors of the energy-momentum tensor in the chiral quark-soliton model

“…The Pauli-Villars regularization is applicable only for mπ = 0 [73]. One popular assumption in literature in the context of modelling GPDs is to assume a generic factorized Ansatz of the type H(x, ξ, t) = H(x, ξ)G(t) where G(t) denotes the respective form factor (other approaches are discussed in [16,76,77,78,79,80]). This assumption implies that the form factors of the EMT should have approximately the same t-dependence as the electromagnetic form factors.…”

Generalized parton distribution function(Eu+Ed)(x,ξ,t)of the nucleon in the ch

“…(17,18) and on the left-hand-sides of Eqs. (21,22) are analogs of the relations between the electric and magnetic form factors G q E (t), G q M (t) and the Dirac-and Pauli-form factors F q 1 (t), F q 2 (t), which are given by…”

“…Current efforts [11] to understand and interpret the data rely, at the early stage of art, on modeling Ansätze for GPDs -which have to comply with the severe general constraints imposed by the polynomiality and positivity properties of GPDs [12,13]. Model calculations [14][15][16][17][18][19][20][21] can provide important guidelines for such Ansätze -in particular in the case of those GPDs for which not even the forward limit is known from deeply inelastic scattering experiments. In this work we study the unpolarized GPD E a (x, ξ, t) in the chiral quark soliton model (χQSM) [22,23].…”