  Mutual entrainment effects in cold neutron-proton mixtures are studied in the
framework of the self-consistent nuclear energy-density functional theory.
Exact expressions for the mass currents, valid for both homogeneous and
inhomogeneous systems, are directly derived from the time-dependent
Hartree-Fock equations with no further approximation. The equivalence with the
Fermi-liquid expression is also demonstrated. Focusing on neutron-star cores, a
convenient and simple analytical formulation of the entrainment matrix in terms
of the isovector effective mass is found, thus allowing to relate entrainment
phenomena in neutron stars to isovector giant dipole resonances in finite
nuclei. Results obtained with different functionals are presented. These
include the Brussels-Montreal functionals, for which unified equations of state
of neutron stars have been recently calculated.
