Coulomb sum rule of A=2, 3, and 4 nuclei

The ω2-weighted sums WL(2)(k) of the longitudinal response of two-, three-, and four-body nuclei are calculated with realistic nuclear forces, and exact (A=2) and variational (A=3 and 4) wave functions. These and the ω-weighted sums WL(k) are used to estimate the unmeasured longitudinal response at ω>Emax. The Coulomb sums obtained by integrating the measured response up to ω=Emax and the estimated response at ω>Emax, are in good agreement with the theoretical predictions in light nuclei. The 3He and 4He data show the presence of proton-proton correlations, although they are not accurate enough to allow for a quantitative determination of the size of the repulsive core in the nucleon-nucleon interaction