  We present a leptogenesis scenario associated with inflationary models
involving non-Abelian gauge fields within the standard model of particle
physics (SM). We show that this class of inflationary models generates
intrinsic birefringent gravitational waves that through the gravitational
chiral anomaly in SM, can naturally create a net lepton number density. The CP
violating interaction is produced by tensor fluctuations of the gauge field,
while the efficiency of this process is determined by the effective background
value of the gauge field. We demonstrate that this mechanism can create the
observed value of baryon to photon number density in a natural range of
parameters of these models.
