  Gravitational leptogenesis is an elegant way of explaining the
matter-antimatter asymmetry in the universe. This paper is a review of the
recently proposed mechanism of radiatively-induced gravitational leptogenesis
(RIGL), in which loop effects in QFT in curved spacetime automatically generate
an asymmetry between leptons and antileptons in thermal quasi-equilibrium in
the early universe. The mechanism is illustrated in a simple see-saw BSM model
of neutrinos, where the lepton-number violating interactions required by the
Sakharov conditions are mediated by right-handed neutrinos with Majorana masses
of O(10^10) GeV. The Boltzmann equations are extended to include new,
loop-induced gravitational effects and solved to describe the evolution of the
lepton number asymmetry in the early universe. With natural choices of neutrino
parameters, the RIGL mechanism is able to generate the observed
baryon-to-photon ratio in the universe today.
