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Moduli Stabilisation and de Sitter String Vacua from Magnetised D7 Branes

D. Cremades, M. P. Garcia del Moral, F. Quevedo, K. Suruliz

TL;DR

This work examines how anomalous U(1)s, ubiquitous in 4D chiral string models, modify moduli stabilisation in IIB flux compactifications with magnetised D7 branes. By deriving the matter spectrum and the effective supergravity action, including FI terms and D-terms, the authors test de Sitter lifting within KKLT-like and Large Volume Scenarios, using explicit examples such as Calabi-Yau $P^4_{[1,1,1,6,9]}$. They show that, in certain setups, a positive D-term can uplift a non-supersymmetric AdS minimum to de Sitter while preserving a controllable 4D EFT, especially when alpha' corrections are included and warping is leveraged. The results indicate a robust stringy mechanism for dS vacua in realistic chiral models, while highlighting model-dependent conditions on cycle selection, flux distribution, and sign choices that govern the success of lifting.

Abstract

Anomalous U(1)'s are ubiquitous in 4D chiral string models. Their presence crucially affects the process of moduli stabilisation and cannot be neglected in realistic set-ups. Their net effect in the 4D effective action is to induce a matter field dependence in the non-perturbative superpotential and a Fayet-Iliopoulos D-term. We study flux compactifications of IIB string theory in the presence of magnetised D7 branes. These give rise to anomalous U(1)'s that modify the standard moduli stabilisation procedure. We consider simple orientifold models to determine the matter field spectrum and the form of the effective field theory. We apply our results to one-modulus KKLT and multi-moduli large volume scenarios, in particular to the Calabi-Yau P^4_{[1,1,1,6,9]}. After stabilising the matter fields, the effective action for the Kahler moduli can acquire an extra positive term that can be used for de Sitter lifting with non-vanishing F- and D-terms. This provides an explicit realization of the D-term lifting proposal of hep-th/0309187.

Moduli Stabilisation and de Sitter String Vacua from Magnetised D7 Branes

TL;DR

This work examines how anomalous U(1)s, ubiquitous in 4D chiral string models, modify moduli stabilisation in IIB flux compactifications with magnetised D7 branes. By deriving the matter spectrum and the effective supergravity action, including FI terms and D-terms, the authors test de Sitter lifting within KKLT-like and Large Volume Scenarios, using explicit examples such as Calabi-Yau . They show that, in certain setups, a positive D-term can uplift a non-supersymmetric AdS minimum to de Sitter while preserving a controllable 4D EFT, especially when alpha' corrections are included and warping is leveraged. The results indicate a robust stringy mechanism for dS vacua in realistic chiral models, while highlighting model-dependent conditions on cycle selection, flux distribution, and sign choices that govern the success of lifting.

Abstract

Anomalous U(1)'s are ubiquitous in 4D chiral string models. Their presence crucially affects the process of moduli stabilisation and cannot be neglected in realistic set-ups. Their net effect in the 4D effective action is to induce a matter field dependence in the non-perturbative superpotential and a Fayet-Iliopoulos D-term. We study flux compactifications of IIB string theory in the presence of magnetised D7 branes. These give rise to anomalous U(1)'s that modify the standard moduli stabilisation procedure. We consider simple orientifold models to determine the matter field spectrum and the form of the effective field theory. We apply our results to one-modulus KKLT and multi-moduli large volume scenarios, in particular to the Calabi-Yau P^4_{[1,1,1,6,9]}. After stabilising the matter fields, the effective action for the Kahler moduli can acquire an extra positive term that can be used for de Sitter lifting with non-vanishing F- and D-terms. This provides an explicit realization of the D-term lifting proposal of hep-th/0309187.

Paper Structure

This paper contains 23 sections, 102 equations, 1 figure.

Table of Contents

  1. Introduction
  2. D-terms and de Sitter vacua
  3. General considerations
  4. On FI terms, anomalous U(1)s and massive gauge bosons
  5. General setup and spectrum
  6. Anomaly cancellation constraints on the spectrum
  7. Explicit Constructions
  8. One modulus case
  9. Two moduli case
  10. Fluxes on the large cycle
  11. Fluxes on the small cycle
  12. Conclusions
  13. Acknowledgements
  14. Anomaly cancellation
  15. $U(1)_a-SU(N_b)^2$ anomalies
  16. ...and 8 more sections

Figures (1)

  • Figure 1: This is a representation of the basic set-up. A set of $n$ D branes is such that one of them is magnetised leading to a $U(n-1)\times U(1)$ gauge group. The dotted lines represent the orientifold plane. Chiral fields are $\varphi$ in the fundamental of $SU(N_c)$ (with $N_c=n-1$) corresponding to strings going from the non-abelian set of branes to the magnetised brane, $\tilde{\varphi}$ in the anti-fundamental, representing strings with endpoints in the non-abelian set of branes and the orientifold image of the magnetised brane and $\rho$ corresponding to strings with endpoints at the magnetised brane and its orientifold image.