Quadratic curvature corrections to stringy effective actions and the absence of de Sitter vacua

TL;DR

This paper examines how quadratic curvature corrections, specifically the Gauss-Bonnet term, influence the existence of de Sitter vacua in heterotic string models, finding that such corrections tend to suppress these solutions.

Contribution

It provides a detailed analysis of the impact of quadratic curvature corrections on de Sitter vacua, showing they decrease the likelihood of such solutions in string-inspired models.

Findings

Quadratic curvature corrections reduce the likelihood of de Sitter vacua.

Perturbative analysis clarifies the effects of Gauss-Bonnet terms.

Inclusion of these corrections makes de Sitter solutions less probable.

Abstract

We investigate the combined effect of fluxes and higher-order curvature corrections, in the form of the Gauss-Bonnet term, on the existence of de Sitter vacua in a heterotic string inspired framework, compactified on spheres and tori. We first gain some intuition on the effects of these corrections by studying a perturbative expansion in the small Gauss-Bonnet coupling. Then, for choices of potential closer to the string theory predictions, we show that the inclusion of quadratic curvature corrections actually reduces the parametric likelihood of de Sitter solutions.