  We present a continuum random phase approximation approach to study electron-
and neutrino-nucleus scattering cross sections, in the kinematic region where
quasielastic scattering is the dominant process. We show the validity of the
formalism by confronting inclusive ($e,e'$) cross sections with the available
data. We calculate flux-folded cross sections for charged-current quasielastic
antineutrino scattering off $^{12}$C and compare them with the MiniBooNE
cross-section measurements. We pay special emphasis to the contribution of
low-energy nuclear excitations in the signal of accelerator-based
neutrino-oscillation experiments.
