String Moduli Stabilization at the Conifold

TL;DR

This work analyzes Type IIB string compactifications near conifold points, showing that in the dilute flux limit one can stabilize the conic modulus $Z$ and the remaining complex-structure moduli and axio-dilaton with exponentially large masses and exponential terms in the effective superpotential that mimic nonperturbative effects. By integrating out the heavy conic modulus and matching onto an effective two-modulus system, the authors demonstrate a consistent combination with the Large Volume Scenario, yielding an exponentially large Calabi–Yau volume and a controlled hierarchy of moduli masses. They further extend the analysis to two-parameter complex-structure manifolds and construct a string-inspired aligned axion inflation scenario, where an inflaton-like axion experiences an enhanced decay constant through flux alignment while remaining compatible with a mild form of the Weak Gravity Conjecture. Overall, the paper provides a mechanism to generate exponential hierarchies without strong warping and outlines a viable path toward inflationary model-building within a controlled EFT framework, while highlighting caveats related to higher-order corrections and full moduli stabilization beyond the simplified setups.

Abstract

We study moduli stabilization for type IIB orientifolds compactified on Calabi-Yau threefolds in the region close to conifold singularities in the complex structure moduli space. The form of the periods implies new phenomena like exponential mass hierarchies even in the regime of negligible warping. Integrating out the heavy conic complex structure modulus leads to an effective flux induced potential for the axio-dilaton and the remaining complex structure moduli containing exponentially suppressed terms that imitate non-perturbative effects. It is shown that this scenario can be naturally combined with the large volume scenario so that all moduli are dynamically stabilized in the dilute flux regime. As an application of this moduli stabilization scheme, a string inspired model of aligned inflation is designed that features a parametrically controlled hierarchy of mass scales.

Figures (2)

• Figure 1: Scalar potential for the two axions $\Sigma$ and $\Theta$ for $f=10$, $h'=\hat{f}'=1$, $h=-\hat{f}=2$, $\hat{C}=1$ and $A=0.1$.
• Figure 2: Scalar potential (dashed lines) for the axion $\Theta$ for $f=10$, $h'=\hat{f}'=1$, $h=-\hat{f}=1$, $\hat{C}=1$, $A=0.1$ and $B=0.01$ in the left-handed plot and $B=0.1$ in the right-handed plot. For comparison, the solid lines show the potential for $B=0$.