Primordial Lepton Oscillations and Baryogenesis

TL;DR

This paper proposes a novel mechanism where primordial lepton oscillations during reheating generate the Universe's baryon asymmetry through flavor-dependent CP violation, without requiring traditional baryogenesis scenarios.

Contribution

It introduces a new leptogenesis mechanism based on flavor oscillations of leptons in the thermal background after inflation, within the seesaw model framework.

Findings

Lepton propagators exhibit flavor mixing in the thermal background.

Flavor-dependent CP violation can produce lepton asymmetry during reheating.

Wash-out processes can preserve the generated asymmetry leading to the observed baryon asymmetry.

Abstract

The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the $CP$ violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.