Nucleon Electromagnetic Form Factors at BESIII

The electromagnetic form factors (EMFFs) of the nucleon represent the simplest structure observables and serve as a testing ground for our understanding of the strong interaction. Using 669 pb(-1) of data collected for a momentum transfer q(2)(= -Q(2)) between 4.0 and 9.5 GeV2, the BESIII experiment obtained the most precise results on the nucleon magnetic form factor G(M) (the EMFF ratio R-em) up to date, with a relative precision of 1.8% (3.4%) for the proton and preliminary results with 8.9% (28%) for the neutron. An interesting oscillating behavior has been observed in the effective FF for both proton and neutron after the subtraction of the dipole-like parameterization, with an almost orthogonal phase difference between proton and neutron, indicating an unknown intrinsic dynamic hidden in the nucleon structure.