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Brane/antibrane dynamics and KKLT stability

Joseph Polchinski

TL;DR

The paper argues that KKLT de Sitter vacua remain metastable when analyzed with appropriate effective field theories that account for brane backreaction and scale separation. It connects ten-dimensional brane dynamics to a four-dimensional EFT using a nilpotent goldstino multiplet to capture SUSY breaking, and it assesses various stability concerns (backreaction, tachyons, finite temperature) as well as no-go theorems. The central claim is that, despite proposed challenges, the KKLT mechanism endures within the established EFT framework, though a fully nonperturbative UV completion of string theory is still lacking. The work emphasizes the need for a more complete, nonperturbative understanding of bulk physics to solidify these conclusions and to map the full landscape of vacua.

Abstract

String theory has few or no stable nonsupersymmetric or de Sitter vacua, only metastable ones. Antibranes are a simple source of supersymmetry breaking, as in the KKLT model, but various arguments have been given that these fail to produce the desired vacua. Proper analysis of the system requires identifying the correct effective field theories at various scales. We find that it reproduces the KKLT conclusions. This is an expanded version of a talk presented at SUSY 2015, Lake Tahoe.

Brane/antibrane dynamics and KKLT stability

TL;DR

The paper argues that KKLT de Sitter vacua remain metastable when analyzed with appropriate effective field theories that account for brane backreaction and scale separation. It connects ten-dimensional brane dynamics to a four-dimensional EFT using a nilpotent goldstino multiplet to capture SUSY breaking, and it assesses various stability concerns (backreaction, tachyons, finite temperature) as well as no-go theorems. The central claim is that, despite proposed challenges, the KKLT mechanism endures within the established EFT framework, though a fully nonperturbative UV completion of string theory is still lacking. The work emphasizes the need for a more complete, nonperturbative understanding of bulk physics to solidify these conclusions and to map the full landscape of vacua.

Abstract

String theory has few or no stable nonsupersymmetric or de Sitter vacua, only metastable ones. Antibranes are a simple source of supersymmetry breaking, as in the KKLT model, but various arguments have been given that these fail to produce the desired vacua. Proper analysis of the system requires identifying the correct effective field theories at various scales. We find that it reproduces the KKLT conclusions. This is an expanded version of a talk presented at SUSY 2015, Lake Tahoe.

Paper Structure

This paper contains 18 sections, 11 equations, 2 figures.

Table of Contents

  1. Introduction
  2. The KKLT construction
  3. Antibrane stability
  4. Brane/flux annihilation, KPV, and singularities
  5. Brane effective field theory
  6. Other issues
  7. The tiny tachyon
  8. NS5 divergences
  9. D6-branes
  10. Finite temperature
  11. A lower barrier?
  12. From ten dimensions to four
  13. From the antibrane to the nilpotent multiplet
  14. Challenges
  15. No-go theorems
  16. ...and 3 more sections

Figures (2)

  • Figure 1: a) Potential for the $AdS_4 \times S^7$ model. b) Potential for the KKLT model. c) Potential for the KKLT model with antibrane.
  • Figure 2: The KPV process a) Antibranes at the bottom of the KS throat, plus D3 charge carried by flux (shaded). b) Antibranes polarized into an NS5, and flux partially neutralized. c) Branes and flux annihilated.