Throwing away antimatter via neutrino oscillations during the reheating era

TL;DR

This paper introduces a novel leptogenesis mechanism during the reheating era, where CP-violating neutrino oscillations create lepton asymmetry that results in the observed matter-antimatter imbalance, with low reheating temperatures.

Contribution

It proposes a new leptogenesis scenario involving flavor oscillations during reheating that does not require fine-tuning of neutrino masses and allows for low reheating temperatures.

Findings

Lepton asymmetry is generated via neutrino oscillations during reheating.

The mechanism works for a broad range of right-handed neutrino masses.

Reheating temperatures can be as low as 10 TeV or 100 GeV depending on the scenario.

Abstract

The simplest possibility to explain the baryon asymmetry of the Universe is to assume that radiation is created asymmetrically between baryons and anti-baryons after the inflation. We propose a new mechanism of this kind where CP-violating flavor oscillations of left-handed leptons in the reheating era distribute the lepton asymmetries partially into the right-handed neutrinos while net asymmetry is not created. The asymmetry stored in the right-handed neutrinos is later washed out by the lepton number violating decays, and it ends up with the net lepton asymmetry in the Standard Model particles, which is converted into the baryon asymmetry by the sphaleron process. This scenario works for a range of masses of the right-handed neutrinos while no fine-tuning among the masses is required. The reheating temperature of the Universe can be as low as $O(10)$~TeV if we assume that the decays of inflatons in the perturbative regime are responsible for the reheating. For the case of the reheating via the dissipation effects, the reheating temperature can be as low as $O(100)$~GeV.