Nucleon structure including high Fock states in AdS/QCD

Abstract

We present a detailed analysis of nucleon electromagnetic and axial form factors in a holographic soft-wall model. This approach is based on an action which describes hadrons with broken conformal invariance and incorporates confinement through the presence of a background dilaton field. For Nc = 3 we describe the nucleon structure in a superposition of a three valence quark state with high Fock states including an adjustable number of partons (quarks, antiquarks and gluons) via studying the dynamics of 5D fermion fields of different scaling dimension in anti-de Sitter (ADS) space. According to the gauge/gravity duality the 5D fermion fields of different scaling dimension correspond to the Fock state components with a specific number of partons. In the present application we restrict to the contribution of 3, 4 and 5 parton components in the nucleon Fock state. With a minimal number of free parameters (dilaton scale parameter, mixing parameters of partial contributions of Fock states, coupling constants in the effective Lagrangian) we achieve a reasonable agreement with data for the nucleon form factors.

Electromagnetic structure of the nucleon and the Roper resonance in a light-front quark approach

“…[71][72][73][74][75][76][77][78][79]. Prediction of the light-front quark model is given by the solid line, results from the AdS/QCD approach [33] are marked by the dotted line. …”

“…The data are from [1,2]. The predictions of the light-front quark model are given by the shortdashed (cos θ =1), and the solid lines (cos θ =0.7); results from the AdS/QCD approach [33] are marked by the dotted line. Nonrelativistic results of Ref.…”

“…1-8). We present a comparison with known data and the soft-wall AdS/QCD approach [33], where elastic nucleon form factors and nucleon-Roper transition form factors have been analyzed in detail. The model generates a Q 2 behavior for…”

“…In Ref. [30] the Roper electroproduction was considered in a soft-wall AdS/QCD model [31][32][33] with inclusion of the leading three-quark (3q) state and higher Fock components.…”

Generalized parton distributions in the soft-wall model of AdS/QCD

“…Gutsche et al [33] have presented a variant of the holographic soft-wall model with the inclusion of higher Fock states. The high Fock states' components are holographically incorporated via studying the dynamics of 5D fermion fields of different scaling dimension in AdS space in accordance with gauge/gravity duality.…”