This talk was part of the Thematic Programme on "The Landscape vs. the Swampland" held at the ESI July 1 -- August 9, 2024.
Flux compactifications that give three- or four-dimensional Anti-de-Sitter vacua with a parametrically-small negative cosmological constant are supposed to be ubiquitous in String Theory. However, the 1+1 and 2+1 dimensional CFT duals to such vacua should have a very large central charges and rather unusual spectra. Furthermore, there are various swampland conjectures that such vacua should not exist. In this talk, I will explain how we construct brane configurations that source the would-be AdS vacua coming out of these flux compactifications, and identify certain UV AdS geometries that these systems of branes source. These place upper bounds on the possible values of the cosmological constants of the scale-separated AdS vacua.
