Branches of the Landscape

TL;DR

This paper explores the flux landscape in string theory, identifying three branches with different supersymmetry breaking scales, and discusses the implications for naturalness and low-energy supersymmetry predictions.

Contribution

It classifies the flux landscape into three branches based on supersymmetry breaking scales and analyzes their implications for string theory predictions and naturalness.

Findings

Most states in the first branch are inaccessible to simple analysis.

Branches two and three offer better prospects for understanding supersymmetry.

The paper discusses how landscape statistics relate to naturalness and low-energy supersymmetry.

Abstract

With respect to the question of supersymmetry breaking, there are three branches of the flux landscape. On one of these, if one requires small cosmological constant, supersymmetry breaking is predominantly at the fundamental scale; on another, the distribution is roughly flat on a logarithmic scale; on the third, the preponderance of vacua are at very low scale. A priori, as we will explain, one can say little about the first branch. The vast majority of these states are not accessible even to crude, approximate analysis. On the other two branches one can hope to do better. But as a result of the lack of access to branch one, and our poor understanding of cosmology, we can at best conjecture about whether string theory predicts low energy supersymmetry or not. If we hypothesize that are on branch two or three, distinctive predictions may be possible. We comment of the status of naturalness within the landscape, deriving, for example, the statistics of the first branch from simple effective field theory reasoning.