Remarks on scale separation in flux vacua

TL;DR

This paper extends the Maldacena-Nunez no-go theorem to exclude certain AdS flux vacua with scale separation, impacting models that attempt to resolve singularities and suggesting a large cosmological hierarchy in four-dimensional compactifications.

Contribution

The authors extend the no-go theorem to exclude AdS vacua with scale separation, challenging certain flux compactification models and their ability to resolve singularities.

Findings

No-go theorem applies to exclude AdS vacua with small Kaluza-Klein scale

Classical resolution of O6 singularities unlikely in scale-separated AdS compactifications

Large cosmological hierarchy implied in four-dimensional compactifications

Abstract

We argue that the Maldacena-Nunez no-go theorem excluding Minkowski and de Sitter vacua in flux compactifications can be extended to exclude anti-de Sitter (AdS) vacua for which the Kaluza-Klein scale is parametrically smaller than the AdS length scale. As a practical application of this observation we demonstrate that the mechanism to resolve O6 singularities in massive type IIA at the classical level is likely not to occur in AdS compactifications with scale separation. We furthermore remark that a compactification to four observable dimensions implies a large cosmological hierarchy.