Is the Coulomb sum rule violated in nuclei?

Guided by the experimental confirmation of the validity of the Effective Momentum Approximation (EMA) in quasi-elastic scattering off nuclei, we have re-examined the extraction of the longitudinal and transverse response functions in medium-weight and heavy nuclei. In the EMA we have performed a Rosenbluth separation of the available world data on ${}^{40}$Ca, ${}^{48}$Ca, ${}^{56}$Fe, ${}^{197}$Au, ${}^{208}$Pb and ${}^{238}$U. We find that the longitudinal response function for these nuclei is “quenched” and that the Coulomb sum is not saturated, at odds with claims in the literature.