Reheating-era leptogenesis

TL;DR

This paper introduces a minimal leptogenesis model during the reheating era, where lepton asymmetry arises from scattering processes involving higher dimensional operators, compatible with various neutrino mass mechanisms.

Contribution

It presents a novel leptogenesis scenario relying solely on the standard model, an inflaton, and higher dimensional operators, without heavy particle decay.

Findings

Successful baryogenesis achieved over a wide parameter range.

Lepton asymmetry generated by scattering, not decay.

Applicable to all neutrino Majorana mass mechanisms.

Abstract

We propose a novel leptogenesis scenario at the reheating era. Our setup is minimal in the sense that, in addition to the standard model Lagrangian, we only consider an inflaton and higher dimensional operators. The lepton number asymmetry is produced not by the decay of a heavy particle, but by the scattering between the standard model particles. After the decay of an inflaton, the model is described within the standard model with higher dimensional operators. The Sakharov's three conditions are satisfied by the following way. The violation of the lepton number is realized by the dimension-5 operator. The complex phase comes from the dimension-6 four lepton operator. The universe is out of equilibrium before the reheating is completed. It is found that the successful baryogenesis is realized for the wide range of parameters, the inflaton mass and reheating temperature, depending on the cutoff scale. Since we only rely on the effective Lagrangian, our scenario can be applicable to all mechanisms to generate neutrino Majorana masses.