Inflation from periodic extra dimensions

TL;DR

This paper proposes a string-inspired supergravity model where periodic extra dimensions generate a multi-natural inflation potential, leading to small field inflation consistent with observational data through a sum of sinusoidal functions.

Contribution

It introduces a novel inflation model derived from string theory with periodic extra dimensions, utilizing world sheet instantons to produce the inflaton potential.

Findings

Inflaton potential modeled as a sum of sinusoidal functions

Numerical predictions align with cosmic observational data

Model demonstrates a UV completion of multi-natural inflation

Abstract

We discuss a realization of a small field inflation based on string inspired supergravities. In theories accompanying extra dimensions, compactification of them with small radii is required for realistic situations. Since the extra dimension can have a periodicity, there will appear (quasi-)periodic functions under transformations of moduli of the extra dimensions in low energy scales. Such a periodic property can lead to a UV completion of so-called multi-natural inflation model where inflaton potential consists of a sum of multiple sinusoidal functions with a decay constant smaller than the Planck scale. As an illustration, we construct a SUSY breaking model, and then show that such an inflaton potential can be generated by a sum of world sheet instantons in intersecting brane models on extra dimensions containing $T^2/{\mathbb Z}_2$ orbifold. We show also predictions of cosmic observables by numerical analyzes.