The Electromagnetic Form Factors of the Proton and Neutron: Fundamental   Indicators of Nucleon Structure
  We present a relativistic interpretation for why the proton's ratio of electric to magnetic form factor falls and for why the ratio of the Pauli to Dirac form factor varies as 1/Q. Reproducing the observed electric form factor of the neutron then mandates the inclusion of the effects of the pion cloud. 
Gerald A. Miller