Tree-Level Stability Without Spacetime Fermions: Novel Examples in String Theory

TL;DR

This paper explores perturbative stability in non-critical, non-supersymmetric string theories without spacetime fermions, presenting new stable examples with specific dimensional invariances and discussing their implications for gauge theories and holography.

Contribution

It introduces novel stable solutions in non-critical string theories lacking spacetime fermions, expanding understanding of stability without supersymmetry or tachyons.

Findings

Presented two non-critical string models with stability and specific dimensional invariance.

Analyzed D-brane embeddings and gauge theory constructions in these backgrounds.

Discussed holographic interpretations and conjectured the role of asymptotic supersymmetry.

Abstract

Is perturbative stability intimately tied with the existence of spacetime fermions in string theory in more than two dimensions? Type 0'B string theory in ten-dimensional flat space is a rare example of a non-tachyonic, non-supersymmetric string theory with a purely bosonic closed string spectrum. However, all known type 0' constructions exhibit massless NSNS tadpoles signaling the fact that we are not expanding around a true vacuum of the theory. In this note, we are searching for perturbatively stable examples of type 0' string theory without massless tadpoles in backgrounds with a spatially varying dilaton. We present two examples with this property in non-critical string theories that exhibit four- and six-dimensional Poincare invariance. We discuss the D-branes that can be embedded in this context and the type of gauge theories that can be constructed in this manner. We also comment on the embedding of these non-critical models in critical string theories and their holographic (Little String Theory) interpretation and propose a general conjecture for the role of asymptotic supersymmetry in perturbative string theory.