We compute the gravitational leptogenesis generated from the parity-violating gravitational waves sourced by an abelian gauge field coupled to a pseudo-scalar inflation. We show that, once the CMB bound on the tensor-to-scalar ratio is enforced, the lepton asymmetry produced by this mechanism during inflation is too small to account for the observed baryon asymmetry of the universe, irrespectively of the inflaton potential, the strength of its coupling to the gauge field, and the details of reheating.
Bibliographical noteFunding Information:
We thank Robert Caldwell for useful discussions. The work of A.P. was partially supported by a summer grant from the graduate program of the School of Astronomy and Physics of the University of Minnesota. The work of M.P. is partially supported from the DOE grant DE-SC0011842 at the University of Minnesota.
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- Cosmological perturbation theory