Universal Axion Backreaction in Flux Compactifications

TL;DR

This paper demonstrates a universal backreaction behavior of large axion fields on their saxion partners in string flux compactifications, using asymptotic Hodge theory to analyze scalar potentials near moduli space boundaries.

Contribution

It introduces a universal pattern in axion backreaction effects in flux compactifications, derived through asymptotic Hodge theory and Newton polygon analysis.

Findings

Universal backreaction pattern identified for large axion fields.

Scalar potentials exhibit a specific structure near moduli space boundaries.

Backreaction effects can be described as Puiseux expansions.

Abstract

We study the backreaction effect of a large axion field excursion on the saxion partner residing in the same $\mathcal{N}=1$ multiplet. Such configurations are relevant in attempts to realize axion monodromy inflation in string compactifications. We work in the complex structure moduli sector of Calabi-Yau fourfold compactifications of F-theory with four-form fluxes, which covers many of the known Type II orientifold flux compactifications. Noting that axions can only arise near the boundary of the moduli space, the powerful results of asymptotic Hodge theory provide an ideal set of tools to draw general conclusions without the need to focus on specific geometric examples. We find that the boundary structure engraves a remarkable pattern in all possible scalar potentials generated by background fluxes. By studying the Newton polygons of the extremization conditions of all allowed scalar potentials and realizing the backreaction effects as Puiseux expansions, we find that this pattern forces a universal backreaction behavior of the large axion field on its saxion partner.