Nucleon electromagnetic form factors from the covariant Faddeev equation

TL;DR

This paper calculates the nucleon's electromagnetic form factors using a covariant Faddeev approach based on Dyson-Schwinger equations, revealing the core quark structure and missing pion-cloud effects at low momentum transfer.

Contribution

It provides a first-principles calculation of nucleon form factors within a covariant framework without additional model assumptions.

Findings

Form factors match experimental data at high momentum transfer.

Evidence of missing pion-cloud effects below ~2 GeV^2.

Reflects properties of the nucleon's quark core.

Abstract

We compute the electromagnetic form factors of the nucleon in the Poincare-covariant Faddeev framework based on the Dyson-Schwinger equations of QCD. The general expression for a baryon's electromagnetic current in terms of three interacting dressed quarks is derived. Upon employing a rainbow-ladder gluon-exchange kernel for the quark-quark interaction, the nucleon's Faddeev amplitude and electromagnetic form factors are computed without any further truncations or model assumptions. The form factor results show clear evidence of missing pion-cloud effects below a photon momentum transfer of ~2 GeV^2 and in the chiral region whereas they agree well with experimental data at higher photon momenta. Thus, the approach reflects the properties of the nucleon's quark core.