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On the DGKT brane dual and its decoupling

Fien Apers

TL;DR

The paper addresses whether scale-separated AdS vacua admit holographic duals by constructing a ten-dimensional brane geometry whose near-horizon limit reproduces the DGKT vacua via flux backtracking and three stacks of intersecting D4-branes. It shows that brane-localized modes are infinitely redshifted relative to asymptotic observers and that graviton fluctuations create an infinite potential barrier near the branes, signaling decoupling from the bulk. The work compares this throat-based decoupling with arguments focusing on the asymptotic region blueshift, arguing that decoupling is robust in the throat even if the asymptotic region behaves differently. It also provides explicit flux quantization and scaling relations, matching the DGKT expectations for vol_S, e^\phi, and the central charge, thereby strengthening the case for a brane-based holographic perspective on scale-separated AdS vacua. Overall, the results clarify the role of near-brane physics in holography for DGKT-like settings and contribute to the broader discourse on holographic duals of scale-separated AdS.

Abstract

It is not understood whether scale-separated AdS vacua in string theory admit a holographic dual. A well-known class of such vacua is provided by the DGKT solutions of massive type IIA string theory, where scale separation arises from large fluxes. In this work, we construct a ten-dimensional brane geometry whose near-horizon limit reproduces the DGKT vacua, using a flux-backtracking approach combined with intersecting D4-brane stacks dual to the unbounded flux sector. We then use this setup to test whether the brane worldvolume theory decouples from the bulk. Modes localised near the branes, deep in the AdS throat, are found to be infinitely redshifted with respect to asymptotic observers. Moreover, an analysis of graviton fluctuations shows the presence of an infinite potential barrier near the branes, providing a direct indication of decoupling. We conclude by comparing these results with recent arguments against decoupling in scale-separated AdS vacua, which focus on the asymptotic region where modes are blueshifted.

On the DGKT brane dual and its decoupling

TL;DR

The paper addresses whether scale-separated AdS vacua admit holographic duals by constructing a ten-dimensional brane geometry whose near-horizon limit reproduces the DGKT vacua via flux backtracking and three stacks of intersecting D4-branes. It shows that brane-localized modes are infinitely redshifted relative to asymptotic observers and that graviton fluctuations create an infinite potential barrier near the branes, signaling decoupling from the bulk. The work compares this throat-based decoupling with arguments focusing on the asymptotic region blueshift, arguing that decoupling is robust in the throat even if the asymptotic region behaves differently. It also provides explicit flux quantization and scaling relations, matching the DGKT expectations for vol_S, e^\phi, and the central charge, thereby strengthening the case for a brane-based holographic perspective on scale-separated AdS vacua. Overall, the results clarify the role of near-brane physics in holography for DGKT-like settings and contribute to the broader discourse on holographic duals of scale-separated AdS.

Abstract

It is not understood whether scale-separated AdS vacua in string theory admit a holographic dual. A well-known class of such vacua is provided by the DGKT solutions of massive type IIA string theory, where scale separation arises from large fluxes. In this work, we construct a ten-dimensional brane geometry whose near-horizon limit reproduces the DGKT vacua, using a flux-backtracking approach combined with intersecting D4-brane stacks dual to the unbounded flux sector. We then use this setup to test whether the brane worldvolume theory decouples from the bulk. Modes localised near the branes, deep in the AdS throat, are found to be infinitely redshifted with respect to asymptotic observers. Moreover, an analysis of graviton fluctuations shows the presence of an infinite potential barrier near the branes, providing a direct indication of decoupling. We conclude by comparing these results with recent arguments against decoupling in scale-separated AdS vacua, which focus on the asymptotic region where modes are blueshifted.
Paper Structure (14 sections, 86 equations, 2 figures, 2 tables)

This paper contains 14 sections, 86 equations, 2 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Construction of the DGKT brane theory
  3. Flux backtracking to find the singularity
  4. Completing the geometry with intersecting D4-brane stacks
  5. Near-horizon limit and matching to DGKT scalings
  6. Decoupling of the DGKT brane theory
  7. Gravitational redshift
  8. Infinite potential barrier
  9. Discussion
  10. Conclusion
  11. More examples of the flux backtracking method
  12. Orbifolds of Freund-Rubin vacua
  13. ABJM vacua: ten-dimensional perspective
  14. Scale-separated AdS$_4$ vacua in massless IIA

Figures (2)

  • Figure 1: Effective potential $V(r)$ for different values of $\omega$.
  • Figure 2: The analysis of Bedroya:2025ltj only considers blueshift in the asymptotic region (left). We point out that there is opposite redshifting behaviour in the AdS throat (right).