The Ubiquitous Throat

TL;DR

This paper statistically analyzes the prevalence of warped throat geometries in string theory vacua, finding that such structures capable of explaining the electroweak hierarchy are common, with shorter throats being statistically unavoidable.

Contribution

It provides a quantitative estimate of the frequency and length distribution of warped throats in the string landscape, focusing on KKLT vacua with many 3-cycles.

Findings

Throats explaining the electroweak hierarchy are common in the landscape.

Shorter throats are statistically unavoidable.

Large fractions of vacua contain multiple warped throats.

Abstract

We attempt to quantify the widely-held belief that large hierarchies induced by strongly-warped geometries are common in the string theory landscape. To this end, we focus on the arguably best-understood subset of vacua -- type IIB Calabi-Yau orientifolds with non-perturbative Kaehler stabilization and a SUSY-breaking uplift (the KKLT setup). Within this framework, vacua with a realistically small cosmological constant are expected to come from Calabi-Yaus with a large number of 3-cycles. For appropriate choices of flux numbers, many of these 3-cycles can, in general, shrink to produce near-conifold geometries. Thus, a simple statistical analysis in the spirit of Denef and Douglas allows us to estimate the expected number and length of Klebanov-Strassler throats in the given set of vacua. We find that throats capable of explaining the electroweak hierarchy are expected to be present in a large fraction of the landscape vacua while shorter throats are essentially unavoidable in a statistical sense.