Insensitivity of flavoured leptogenesis to low energy CP violation

TL;DR

This paper demonstrates that in flavoured leptogenesis models, the generated baryon asymmetry does not depend on low-energy CP-violating phases, making leptogenesis viable regardless of observable neutrino CP violation.

Contribution

It proves that the baryon asymmetry in leptogenesis is insensitive to PMNS phases even when flavour effects are considered, extending previous results.

Findings

Baryon asymmetry is unaffected by low-energy CP phases.

Flavour effects do not alter the insensitivity of leptogenesis to PMNS phases.

Leptogenesis can succeed regardless of observable CP violation in the lepton sector.

Abstract

If the baryon asymmetry of the Universe is produced by leptogenesis, CP violation is required in the lepton sector. In the seesaw extension of the Standard Model with three hierarchical right-handed neutrinos, we show that the baryon asymmetry is insensitive to the PMNS phases: thermal leptogenesis can work for any value of the observable phases. This result was well-known when there are no flavour effects in leptogenesis; we show that it remains true when flavour effects are included.