Non-tachyonic Scherk-Schwarz compactifications, cosmology and moduli stabilization

TL;DR

This paper explores tachyon-free Scherk-Schwarz compactifications in string theory, presenting explicit models with broken supersymmetry and analyzing their cosmological implications and moduli stabilization mechanisms.

Contribution

It provides explicit examples of tachyon-free compactifications with broken supersymmetry and discusses their cosmological and moduli stabilization properties.

Findings

Constructed explicit tachyon-free models in various dimensions.

Demonstrated moduli stabilization via nonperturbative effects.

Analyzed cosmological solutions within these frameworks.

Abstract

It is well-known that Scherk-Schwarz compactifications in string theory have a tachyon in the closed string spectrum appearing for a critical value of a compact radius. The tachyon can be removed by an appropriate orientifold projection in type II strings, giving rise to tachyon-free compactifications. We present explicit examples of this type in various dimensions, including six and four-dimensional chiral examples, with softly broken supersymmetry in the closed sector and non-BPS configurations in the open sector. These vacua are interesting frameworks for studying various cosmological issues. We discuss four-dimensional cosmological solutions and moduli stabilization triggered by nonperturbative effects like gaugino condensation on D-branes and fluxes.