Helicity skewed quark distributions of the nucleon and chiral symmetry

Abstract

We compute the helicity skewed quark distributions H and E in the chiral quark-soliton model of the nucleon. This model emphasizes correctly the role of spontaneously broken chiral symmetry in structure of nucleon. It is based on the large-N c picture of the nucleon as a soliton of the effective chiral lagrangian and allows to calculate the leading twist quarkand antiquark distributions at a low normalization point.We discuss the role of chiral symmetry in the helicity skewed quark distributions H and E. We show that generalization of soft pion theorems, based on chiral Ward identities, leads in the region of −ξ < x < ξ to the pion pole contribution to E which dominates at small momentum transfer.

Linking generalized parton distributions to constituent quark models

“…Would higher Fock states (including gluons and antiquarks) be included, nonvanishing GPD's should occur for x < ξ with x = ξ as a cross-over point (see, e.g., Ref. [21,22]). …”

“…The first model calculations were performed using the MIT bag model [20]. Further calculations have been performed in the chiral quark-soliton model [21,22].…”

A detailed next-to-leading order QCD analysis of deeply virtual Compton scattering observables

“…It appears to be valid at small x and small t, from the HERA data on a variety of diffractive measurements. However, it appears not to hold for moderate to large t and larger x [39].…”

“…(37,38) and eqs. (39,40) sample the input PDFs all the way down to zero in x . Generally speaking, the providers of PDF sets issue programs that only allow their PDFs to be called for x greater than some minimum value.…”

“…(37,38) and eqs. (39,40) for the DGLAP and ERBL regions respectively, employing an adaptive Gaussian numerical integration routine on a non-equidistant grid 14 . We comment further on our usage of grids and integration routines below.…”