  We show that nuclear sigma, omega, and pi mesons can contribute coherently to
enhance the electroproduction cross section on nuclei for longitudinal virtual
photons at low Q^2 while depleting the cross section for transverse photons. We
are able to describe recent HERMES inelastic lepton-nucleus scattering data at
low Q^2 and small x using photon-meson and meson-nucleus couplings which are
consistent with (but not determined by) existing constraints from meson decay
widths, nuclear structure, deep inelastic scattering, and lepton pair
production data. We find that while nuclear-coherent pion currents are not
important for the present data, they could be observed at different kinematics.
Our model for coherent meson electroproduction requires the assumption of
mesonic currents and couplings which can be verified in separate experiments.
The observation of nuclear-coherent mesons in the final state would verify our
theory and allow the identification of a specific dynamical mechanism for
higher-twist processes.
