Low-energy excitations and quasielastic contribution to electron-nucleus and neutrino-nucleus scattering in the continuum random-phase approximation

We present a detailed study of a continuum random-phase approximation approach to quasielastic electron-nucleus and neutrino-nucleus scattering. We compare the (e,e') cross-section predictions with electron scattering data for the nuclear targets ¹²C, ¹⁶O, and ⁴⁰Ca, in the kinematic region where quasielastic scattering is expected to dominate. We examine the longitudinal and transverse contributions to ¹²C(e,e') and compare them with the available data. We find an overall satisfactory description of the (e,e') data. Further, we study the ¹²C(ν_μ,μ^-) cross sections relevant for accelerator-based neutrino-oscillation experiments. We pay special attention to low-energy excitations which can account for non-negligible contributions in measurements, and require a beyond-Fermi-gas formalism.