Neutron charge density from simple pion cloud models

Abstract

The physical nucleon is modeled as a bare nucleon surrounded by a pion cloud using a psuedoscalar pion-nucleon coupling to examine its implications for the neutron form factor, F{sub 1}(Q{sup 2}), and the corresponding transverse charge density, {rho}(b), in the infinite momentum frame. Two versions, one with a tunable Pauli-Villars parameter and another with light-front cloudy-bag pion-nucleon form factors, are examined. A qualitative agreement with the experimental form factor (F{sub 1}<0 for all Q{sup 2}) and transverse charge density is achieved when the nucleon is treated as having a finite extent. The bare nucleon must have a finite extent if this model is to account for a negative definite F{sub 1} and consequently a negative transverse charge density of the neutron at its center.