  We present quasi-elastic neutrino-nucleus cross sections in the energy range
from 150 MeV up to 5 GeV for the target nuclei 12C and 56Fe. A relativistic
description of the nuclear dynamics and the neutrino-nucleus coupling is
adopted. For the treatment of final-state interactions (FSI) we rely on two
frameworks succesfully applied to exclusive electron-nucleus scattering: a
relativistic optical potential and a relativistic multiple-scattering Glauber
approximation. At lower energies, the optical-potential approach is considered
to be the optimum choice, whereas at high energies a Glauber approach is more
natural. Comparing the results of both calculations, it is found that the
Glauber approach yields valid results down to the remarkably small nucleon
kinetic energies of 200 MeV. We argue that the nuclear transparencies extracted
from A(e,e'p) measurements can be used to obtain realistic estimates of the
effect of FSI mechanisms on quasi-elastic neutrino-nucleus cross sections. We
present two independent relativistic plane-wave impulse approximation (RPWIA)
calculations of quasi-elastic neutrino-nucleus cross sections. They agree at
the percent level, showing the reliability of the numerical techniques adopted
and providing benchmark RPWIA results.
