Nucleon electromagnetic form factor ratio at low Q 2 : The JLab experimental Program

The nucleon electromagnetic form factors encode information about their complex internal structure. At low Q2 the form factors probe the peripheral structure of the nucleon and are related to the charge and magnetization distributions and radii. Several experiments at JLab have probed the low Q2 form factors, producing a wealth of data. In particular, new, very precise measurements of the proton form factor ratio at very low Q2 have shown a strong deviation from unity at lower values than previously observed. This low Q2 behavior is unanticipated by theoretical calculations. Even newer, more precise measurements are underway and are expected to provide results with unprecedented precision down to Q2 sim 0.15 GeV2.