Flavor Decomposition of the Elastic Nucleon Electromagnetic Form Factors

The u- and d-quark contributions to the elastic nucleon electromagnetic form factors have been determined by using experimental data on GEⁿ, GMⁿ, GEᵖ, and GMᵖ. Such a flavor separation of the form factors became possible up to negative four-momentum transfer squared Q²=3.4 GeV² with recent data on GEⁿ from Hall A at Jefferson Lab. For Q² above 1 GeV², for both the u and the d quark, the ratio of the Pauli and Dirac form factors, F₂/F₁, was found to be almost constant in sharp contrast to the behavior of F₂/F₁ for the proton as a whole. Also, again for Q²>1 GeV², both F₂ᵈ and F₁ᵈ are roughly proportional to 1/Q⁴, whereas the dropoff of F₂ᵘ and F₁ᵘ is more gradual.