  We review the recent progress made in the computation of electromagnetic
response functions in light and medium-mass nuclei using coupled-cluster
theory. We show how a many-body formulation of the Lorentz integral transform
method allows to calculate the photoabsorption cross sections of $^{16, 22}$O
and $^{40}$Ca. Then, we discuss electromagnetic sum rules, with particular
emphasis on the electric dipole polarizability, $\alpha_D$. By including
triples corrections in coupled-cluster theory, we revisit $^{48}$Ca, for which,
beside the electric dipole polarizability, we had previously investigated the
neutron and proton radii, as well as the size of the neutron-skin thickness
[1]. We show that correlations among these observables still hold, albeit a
better agreement with experiment is obtained for $\alpha_D$ and the prediction
of a small neutron-skin thickness is further corroborated.
