Old Inflation in String Theory

TL;DR

This paper introduces a string theory-based inflation model that avoids slow-roll conditions by utilizing warped compactifications and anti-D3-branes, providing a novel approach to early universe inflation.

Contribution

It presents a new string-inspired inflation scenario using warped geometries and anti-D3-branes, eliminating the need for a slow-roll inflaton potential.

Findings

Inflation driven by false vacuum with positive energy density.

Graceful exit achieved via anti-D3-branes migrating from ultraviolet to infrared.

Cosmological perturbations generated through the curvaton mechanism.

Abstract

We propose a stringy version of the old inflation scenario which does not require any slow-roll inflaton potential and is based on a specific example of string compatification with warped metric. Our set-up admits the presence of anti-D3-branes in the deep infrared region of the metric and a false vacuum state with positive vacuum energy density. The latter is responsible for the accelerated period of inflation. The false vacuum exists only if the number of anti-D3-branes is smaller than a critical number and the graceful exit from inflation is attained if a number of anti-D3-branes travels from the ultraviolet towards the infrared region. The cosmological curvature perturbation is generated through the curvaton mechanism.