  Radiatively-induced gravitational leptogenesis is a potential mechanism to
explain the observed matter-antimatter asymmetry of the universe. Gravitational
tidal effects at the quantum loop level modify the dynamics of the leptons in
curved spacetime and may be encoded in a low-energy effective action Seff. It
has been shown in previous work how in a high-scale BSM theory the CP odd
curvature-induced interactions in Seff modify the dispersion relations of
leptons and antileptons differently in an expanding universe, giving rise to an
effective chemical potential and a non-vanishing equilibrium lepton-antilepton
asymmetry. In this paper, the CP even curvature interactions are shown to break
lepton number current conservation and modify the evolution of the lepton
number density as the universe expands. These effects are implemented in a
generalised Boltzmann equation and used to trace the dynamical evolution of the
lepton number density in different cosmological scenarios. The theory predicts
a potentially significant gravitationally-induced lepton-antilepton asymmetry
at very early times in the evolution of the universe.
