Kahler moduli double inflation

TL;DR

This paper demonstrates that double inflation naturally occurs in Kähler moduli inflation models, leading to a peak in the primordial power spectrum that improves the fit to observational CMB data.

Contribution

It introduces a novel realization of double inflation within string-inspired Kähler moduli models, highlighting the role of parametric resonance in generating observable features.

Findings

Power spectrum exhibits a peak on observable scales.

Peak in power spectrum improves fit to WMAP 7-year data.

Numerical calculations confirm the amplification of perturbations.

Abstract

We show that double inflation is naturally realized in K\"ahler moduli inflation, which is caused by moduli associated with string compactification. We find that there is a small coupling between the two inflatons which leads to amplification of perturbations through parametric resonance in the intermediate stage of double inflation. This results in the appearance of a peak in the power spectrum of the primordial curvature perturbation. We numerically calculate the power spectrum and show that the power spectrum can have a peak on observationally interesing scales. We also compute the TT-spectrum of CMB based on the power spectrum with a peak and see that it better fits WMAP 7-years data.