Logarithmic loop corrections, moduli stabilisation and de Sitter vacua in string theory

TL;DR

This paper investigates string loop corrections in type IIB compactifications, revealing a logarithmic behavior that enables a novel moduli stabilization mechanism leading to de Sitter vacua, challenging existing swampland conjectures.

Contribution

It introduces a new perturbative moduli stabilization mechanism using logarithmic loop corrections, avoiding non-perturbative effects and providing a counterexample to swampland conjectures.

Findings

Logarithmic behavior of loop corrections in large volume limit

Explicit stabilization of Kähler moduli without non-perturbative effects

Realization of de Sitter vacua consistent with string theory constraints

Abstract

We study string loop corrections to the gravity kinetic terms in type IIB compactifications on Calabi-Yau threefolds or their orbifold limits, in the presence of $D7$-branes and orientifold planes. We show that they exhibit in general a logarithmic behaviour in the large volume limit transverse to the $D7$-branes, induced by a localised four-dimensional Einstein-Hilbert action that appears at a lower order in the closed string sector, found in the past. Here, we compute the coefficient of the logarithmic corrections and use them to provide an explicit realisation of a mechanism for K\"ahler moduli stabilisation that we have proposed recently, which does not rely on non-perturbative effects and lead to de Sitter vacua. Our result avoids no-go theorems of perturbative stabilisation due to runaway potentials, in a way similar to the Coleman-Weinberg mechanism, and provides a counter example to one of the swampland conjectures concerning de Sitter vacua in quantum gravity, once string loop effects are taken into account; it thus paves the way for embedding the Standard Model of particle physics and cosmology in string theory.