Open Strings and Supersymmetry Breaking

TL;DR

This paper reviews mechanisms for supersymmetry breaking in orientifold models, emphasizing non-supersymmetric open-string solutions where vacuum energy can be tuned via extra dimensions.

Contribution

It provides a comprehensive review of supersymmetry breaking mechanisms in orientifold models, highlighting the role of open-string solutions and extra dimensions.

Findings

One-loop vacuum energy can be tuned by the size of extra dimensions.

Non-supersymmetric open-string solutions are consistent flat-space solutions.

Vacuum energy can be made arbitrarily small with sufficiently large extra dimensions.

Abstract

We review several mechanisms for supersymmetry breaking in orientifold models. In particular, we focus on non-supersymmetric open-string realisations that correspond to consistent flat-space solutions of the classical equations of motion. In these models, the one-loop vacuum energy can typically fixed by the size of the compact extra dimensions, and can thus be tuned to extremely small values if enough extra dimensions are large.