Inflationary Affleck-Dine Scalar Dynamics and Isocurvature Perturbations

TL;DR

This paper analyzes the evolution of the Affleck-Dine scalar during inflation, predicting baryonic isocurvature perturbations that could be observed in the CMB, with implications for inflation models and structure formation.

Contribution

It provides a detailed analysis of Affleck-Dine scalar dynamics during inflation and predicts observable isocurvature perturbations in the CMB.

Findings

In D-term inflation, the Affleck-Dine scalar reaches a fixed value with minimal dependence on e-foldings.

Predicted isocurvature contribution to CMB is 0.01-0.1, observable by PLANCK.

In F-term inflation, isocurvature perturbations depend on the inflationary Hubble parameter.

Abstract

We consider the evolution of the Affleck-Dine scalar during D-term and F-term inflation and solve the combined slow-roll equations of motion. We show that for a typical case, where both the Affleck-Dine scalar and inflaton initially have large values, in D-term inflation the Affleck-Dine scalar is driven to a fixed value, with only a very slight dependence on the number of e-foldings. As a result, there is a definite prediction for the ratio of the baryonic isocurvature perturbation to the adiabatic perturbation. In minimal (d=4) Affleck-Dine baryogenesis the relative isocurvature contribution to the CMB angular power spectrum amplitude is predicted to be in the range $0.01-0.1$, which can account for present large-scale structure observations and should be observable by PLANCK. In a very general case, scale-invariance of the adiabatic perturbations from the Affleck-Dine scalar imposes a lower bound of about 0.01 for d=4. For d=6 the isocurvature perturbation may just be observable, although this is less certain. We also consider F-term inflation and show that the magnitude of the baryonic isocurvature perturbation is fixed by the value of $H$ during inflation. For typical values of $H$ the isocurvature perturbation could be close to present observational limits.