On Nucleon Electromagnetic Form Factors: A Précis

Electron scattering at large Q2 probes a nucleon's quark core. This core's contribution to electromagnetic form factors may be calculated using Poincaré covariant Faddeev amplitudes combined with a nucleon-photon vertex that automatically fulfills a Ward-Takahashi identity for on-shell nucleons. The calculated behaviour of GEp(Q2)/GMp(Q2) on Q2∈[2,6] GeV2 agrees with that inferred from polarisation transfer data, and exhibits a zero at Q2≈6.5 GeV2. There is some evidence that F2(Q2)/F1(Q2)∝[lnQ2/Λ2]2/Q2 for Q2≳6 GeV2.