Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

What if string theory has no de Sitter vacua?

Ulf H. Danielsson, Thomas Van Riet

TL;DR

The paper questions the existence of de Sitter vacua in string theory after two decades of model-building, arguing that rigorous 4D dS solutions are not robustly established and that many proposed constructions rely on uncontrolled backreaction or questionable assumptions. It surveys classical, non-geometric, and quantum approaches across string theories (notably IIB), highlighting KKLT, LVS, and uplift mechanisms while emphasizing persistent problems such as tachyons, backreaction, and consistency with swampland criteria. The authors advocate a shift in perspective, considering the possibility that string theory may inherently disfavor de Sitter space and suggesting alternative explanations for dark energy, as well as exploring AdS landscapes and potential dS/CFT frameworks. They conclude by calling for open-minded scrutiny, explicit counterexamples, and integration with the swampland program to better understand the cosmological constant problem within quantum gravity.

Abstract

We present a brief overview of attempts to construct de Sitter vacua in string theory and explain how the results of this 20-year endeavor could point to the fact that string theory harbors no de Sitter vacua at all. Making such a statement is often considered controversial and "bad news for string theory". We discuss how perhaps the opposite can be true.

What if string theory has no de Sitter vacua?

TL;DR

The paper questions the existence of de Sitter vacua in string theory after two decades of model-building, arguing that rigorous 4D dS solutions are not robustly established and that many proposed constructions rely on uncontrolled backreaction or questionable assumptions. It surveys classical, non-geometric, and quantum approaches across string theories (notably IIB), highlighting KKLT, LVS, and uplift mechanisms while emphasizing persistent problems such as tachyons, backreaction, and consistency with swampland criteria. The authors advocate a shift in perspective, considering the possibility that string theory may inherently disfavor de Sitter space and suggesting alternative explanations for dark energy, as well as exploring AdS landscapes and potential dS/CFT frameworks. They conclude by calling for open-minded scrutiny, explicit counterexamples, and integration with the swampland program to better understand the cosmological constant problem within quantum gravity.

Abstract

We present a brief overview of attempts to construct de Sitter vacua in string theory and explain how the results of this 20-year endeavor could point to the fact that string theory harbors no de Sitter vacua at all. Making such a statement is often considered controversial and "bad news for string theory". We discuss how perhaps the opposite can be true.

Paper Structure

This paper contains 21 sections, 32 equations, 1 figure.

Table of Contents

  1. Introduction
  2. dS constructions in string sofar
  3. Conceptual framework
  4. Classification scheme
  5. Classical
  6. Non-geometric
  7. Quantum
  8. IIB string theory
  9. Other string theories
  10. They all have problems?
  11. Classical
  12. Non-geometric
  13. Quantum
  14. Anti-brane backreaction inside extra dimensions
  15. Anti-brane backreaction on the moduli
  16. ...and 6 more sections

Figures (1)

  • Figure 1: An attempt to classify de Sitter constructions in string theory