The Pion-Cloud Contribution to the Electromagnetic Nucleon Form Factors

TL;DR

This paper investigates the electromagnetic structure of the nucleon using a relativistic quark model that includes meson cloud effects, finding significant contributions at low momentum transfer.

Contribution

It introduces a hybrid constituent-quark model with a Poincaré-invariant multichannel approach, highlighting the meson-cloud's role below 0.5 GeV^2.

Findings

Meson-cloud contribution is about 10% at Q^2→0.

The model reproduces nucleon form factors reasonably well.

Meson effects are significant only at low Q^2.

Abstract

We study the electromagnetic structure of the nucleon within a hybrid constituent-quark model that comprises, in addition to the $3q$ valence component, also a $3q$+$\pi$ non-valence component. To this aim we employ a Poincar\'e-invariant multichannel formulation based on the point-form of relativistic quantum mechanics. With a simple 3-quark wave function for the bare nucleon, i.e. the $3q$-component, we obtain reasonable results for the nucleon form factors and predict the meson-cloud contribution to be significant only below $Q^2\lesssim 0.5$\,GeV$^2$ amounting to about 10\% for $Q^2\rightarrow 0$, in accordance with the findings of other authors.