Quasi-elastic electron scattering from light nuclei

While the longitudinal quasi-elastic response function is satisfactorily understood, the excess in the transverse response remained a puzzle. For light nuclei, where this excess is largest, we determine the separated response functions from an analysis of the world data on quasi-elastic inclusive electron scattering. The corresponding Euclidean response functions are derived and compared to those calculated with Green's function Monte Carlo methods, using realistic interactions and currents. Large contributions associated with two-body currents are found for the transverse response, in agreement with data. The contributions of two-body charge and current operators in the ³He, ⁴He, and ⁶Li response functions are also studied via sum rule techniques. We find in particular that the large enhancement can only be understood if in the description of the initial (bound) and the final (continuum) state the tensor- and short range n-p correlations are included.