Is There A String Theory Landscape

TL;DR

This paper critically examines the landscape of flux compactification solutions in string theory, discussing their plausibility, limitations, and implications for real-world physics, especially regarding the anthropic principle and supersymmetry.

Contribution

It provides a detailed analysis of the viability of flux compactifications, highlighting the challenges in obtaining stable de Sitter solutions and their implications for phenomenology.

Findings

AdS solutions are plausible within flux compactifications.

Meta-stable dS solutions often involve breakdown of effective field theory.

Anthropic reasoning suggests low energy supersymmetry breaking, but many features may conflict with experiments.

Abstract

We examine recent claims of a large set of flux compactification solutions of string theory. We conclude that the arguments for AdS solutions are plausible. The analysis of meta-stable dS solutions inevitably leads to situations where long distance effective field theory breaks down. We then examine whether these solutions are likely to lead to a description of the real world. We conclude that one must invoke a strong version of the anthropic principle. We explain why it is likely that this leads to a prediction of low energy supersymmetry breaking, but that many features of anthropically selected flux compactifications are likely to disagree with experiment.