Nucleon electromagnetic form factors at large momentum from Lattice QCD

Proton and neutron electric and magnetic form factors, G_E and G_M, are the primary characteristics of their spatial structure. Their behavior at large values of the momentum transfer Q² may enlighten us on the QCD dynamics in transition from nonperturbative to perturbative regime and effects of quark orbital angular momenta and diquark correlations in particular. Several experiments at JLab and elsewhere are focussing on the momentum region up to Q²=18 GeV² for the proton and up to 14 GeV² for the neutron. I will report our study of nucleon electromagnetic form factors with momenta up to Q²=12 GeV² on a lattice with a range of parameters approaching physical values. The G_E/G_M form factor ratios and flavor contributions are in reasonable agreement with experiment. Comparison to new JLab results will be an important test of lattice QCD methods in the near-perturbative regime.