Sum rules for electron nucleus scattering

The interaction of electrons with nuclei is well understood and sufficiently weak to allow the separation of nuclear structure aspects from those connected with the reaction itself. Nevertheless the complexity of the nuclear spectrum remains as a stumbling block for a simple interpretation of the large mass of experimental data. Sum rules, which wash out the details of nuclear excited states, allow us to remain with the basic features of the nucleus. The rather long history of electronuclear sum rules has proved the power of the method, while the recent progress made in the many-body problem, together with the high accuracy of electron scattering data have transformed the sum rule techniques into stringent tests for nuclear theories and experiments.