Primordial Dirac Leptogenesis

TL;DR

This paper proposes a new model of Dirac leptogenesis occurring during the early universe's reheating phase, linking inflaton decay asymmetries to baryon asymmetry and predicting observable effects on relativistic species.

Contribution

It introduces a minimal mechanism for Dirac leptogenesis that naturally explains small neutrino Yukawa couplings and predicts testable cosmological signatures.

Findings

Asymmetry transfer from inflaton decay to neutrinos and baryons demonstrated.

Model predicts contributions to $N_{\text{eff}}$ detectable in future observations.

Provides a consistent framework for Dirac leptogenesis during reheating.

Abstract

We present a novel realization of Dirac leptogenesis based on the post-inflationary reheating phase of the early universe. An asymmetry generated within the scalar sector via CP-violating and out-of-equilibrium inflaton decays is transferred to chiral neutrinos through Yukawa interactions and then to baryons via electroweak sphalerons. We describe in detail a minimal realization of this mechanism that naturally accommodates small neutrino Yukawa couplings and results in contributions to the effective number of relativistic species, $N_{\text{eff}}$, testable in upcoming cosmological observations.