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 G(E)(n), G(M)(n), G(E)(p), and G(M)(p). Such a flavor separation of the form factors became possible up to negative four-momentum transfer squared Q(2) = 3.4 GeV2 with recent data on G(E)(n) from Hall A at Jefferson Lab. For Q(2) above 1 GeV2, for both the u and the d quark, the ratio of the Pauli and Dirac form factors, F-2/F-1, was found to be almost constant in sharp contrast to the behavior of F-2/F-1 for the proton as a whole. Also, again for Q(2) > 1 GeV2, both F-2(d) and F-1(d) are roughly proportional to 1/Q(4), whereas the dropoff of F-2(u) and F-1(u) is more gradual.