Neutrino reheating predictions with non-thermal leptogenesis

TL;DR

This paper investigates how non-thermal leptogenesis via inflaton decay influences neutrino reheating, linking inflationary parameters with baryon asymmetry and spectral index to refine early Universe models.

Contribution

It refines previous models by analyzing neutrino reheating dynamics and connecting inflationary observables with baryon asymmetry in a natural framework.

Findings

Neutrino reheating duration can be calculated generally.

Inflationary observables are consistent with neutrino reheating across models.

Baryon asymmetry and spectral index are directly linked.

Abstract

Connecting inflation with neutrino physics through non-thermal leptogenesis via direct inflaton-right-handed neutrino (RHN) coupling naturally incorporates neutrino reheating, leaving no ambiguity regarding the early history of the Universe. In ref.~\cite{Zhang:2023oyo}, we demonstrate that non-thermal leptogenesis from inflaton decay expands the viable parameter space compared to thermal leptogenesis and provides a natural link to inflation. In this work, we refine our previous findings by closely examining the dynamics of neutrino reheating. We first calculate the duration of neutrino reheating on a general basis, then analyze inflationary observables consistent with neutrino reheating across four models, establishing a direct connection between baryon asymmetry and the spectral index. This approach places these two important observables on the same plane and yields specific predictions that help break the degeneracy among inflationary models. The well-motivated and economical framework offers a simple, natural, and testable description of the early Universe.