  In this talk we present a mechanism for leptogenesis which is based on
gravity waves produced during inflation. We show that when inflation is driven
by a pseudo-scalar field the metric perturbations generated during inflation
can become birefringent, therefore giving a non-vanishing contribution to the
gravitational triangle anomaly and sourcing lepton anti-lepton asymmetry. As
this asymmetry is sourced by the fields which are active during inflation, it
is not washed out or diluted by inflation. The amount of matter asymmetry
generated in our model can be of realistic size for the parameters within the
range of some inflationary scenarios and grand unified theories. This talk is
based on Ref.[1] which has appeared on the arXiv as hep-th/0403069.
