Affleck-Dine Leptogenesis with Varying Peccei-Quinn Scale

TL;DR

This paper explores how a varying Peccei-Quinn scale during the early universe can enhance Affleck-Dine leptogenesis efficiency, linking baryon asymmetry to the mu-term and suppressing axion isocurvature perturbations.

Contribution

It introduces a supersymmetric DFSZ model with a large PQ scale during leptogenesis, relaxing neutrino mass constraints and connecting baryogenesis to electroweak fine-tuning.

Findings

Leptogenesis efficiency increases with a larger PQ scale during lepton number generation.

The baryon asymmetry is related to the mu-term, linking it to electroweak fine-tuning.

Axion isocurvature perturbations are naturally suppressed in this scenario.

Abstract

The Affleck-Dine leptogenesis scenario along the LHu flat direction is reconsidered. It is known that successful Affleck-Dine leptogenesis requires that the lightest neutrino mass is extremely small. This situation can be significantly relaxed if the neutrino mass in the early universe is different from the present one. We consider a supersymmetric Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) type model, which provides a solution to the strong CP problem and generates a SUSY mu-term and right-handed neutrino masses. If the PQ scale during lepton number generation is much larger than the present value, leptogenesis is very efficient so that enough baryon number can be generated without introducing a hierarchically small neutrino mass. The final baryon asymmetry is related to the mu-term, and hence linked to the level of electroweak fine-tuning. We also show the PQ breaking scalar dynamics that keeps a large PQ breaking scale during inflation and lepton number generation. The mu-term generating superpotential plays an important role for preserving the lepton asymmetry during saxion oscillation. In this scenario, the axion isocurvature perturbation is naturally suppressed.