arXiv subjects

Colin Sterckx

Publications and source records attributed to Colin Sterckx.

14 recordsLinked to original sources

arXiv2026

de Sitter and S-folds in type IIB from $\mathcal{N} = 4$ $D = 4$ gauged supergravity

In this paper, we classify the type IIB uplifts of the $\mathcal{N}=4$ $D=4$ pure $\text{SO}(4)$-gauged supergravity admitting a dS$_4$ solution. As for their AdS cousins, the internal geometries of these uplifts consist of two $S^2$ fibred over a Riemann surface $\Sigma$, and are classified by pairs of harmonic functions $h_{1,\,2}$ on $\Sigma$, providing a new family of de Sitter solutions in type IIB. Choosing specific functions $h_{1,\,2}$ on $\Sigma = \mathbb{R} \times I$, we perform an S-fold quotient of the internal space along its non-compact direction. This S-folding allows us to evade the assumptions of the Maldacena-Nunez no-go theorem and provides a classical de Sitter solution of type IIB supergravity with finite and non-vanishing four-dimensional effective Newton constant.

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arXiv2026

R7-branes and AdS$_{\text{9}}$ solutions in type IIB

We consider the recently found $\mathrm{AdS}_9$ backgrounds in type IIB supergravity. We start by reviewing the solutions in a more convenient set of coordinates, which allows us to explicitly compute a few relevant observables, including the holographic central charge. Subsequently, we study non-supersymmetric 7-brane configurations sourced by the IIB axio-dilaton. We find explicit analytic 7-brane solutions that possess the above $\mathrm{AdS}_9$ backgrounds as their near-horizon geometry. Finally, we discuss the relation of these 7-brane solutions to the R7 branes by imposing the reflection monodromy $\tau \rightarrow -\bar \tau$ in the transverse plane.

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arXiv2026

Consistent Truncations from Duality Symmetries and Desingularization of Orbifold Uplifts

This paper is an extension of the results presented in \cite{Guarino:2024gke}. We study $ G_S$-invariant subsectors of maximal gauged supergravities and show that such models can provide consistent truncations even when $G_S$ is not a symmetry of the original supergravity. We show that this construction is key to building pure supergravities around a supersymmetric AdS$_D$ solution. We illustrate this construction by building a consistent $\mathcal{N}=4$ subsector of the $D=4$ $\mathcal{N}=8$ $[\mathrm{SO}(6)\times \mathrm{SO}(1,1)]\ltimes \mathbb{R}^{12}$ gauged supergravity. We use this result to build the uplift of the multicharge spindle solutions in type IIB and we define a simple criterion for assessing the regularity of the uplift. We show that the type IIB uplift of the spindle is always non-regular, admitting eight codimension-six orbifold singularities. We apply the same criterion to other spindle uplifts, recovering known results and making predictions on the regularity of spindles on (quasi-)regular SE$_7$ manifolds.

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arXiv2025

How to uplift non-maximal gauged supergravities

In this paper, we provide an algorithm to perform the uplift of non-maximal $G_g$-gauged supergravities to type IIB or 11D supergravities. Using tools of exceptional field theory and generalised geometry, we show that the internal manifold admits a $G_g$-action, and that consistency of the uplift is equivalent to solving a simpler PDE on the quotient $M_{\text{int}}/G_g$. As an application, we classify all possible uplifts of pure half-maximal four-dimensional $\textrm{SO}(4)$-gauged supergravity to type IIB and we recover consistent truncations around any of the D'Hoker-Estes-Gutperle solutions \cite{DHoker:2007hhe}.

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arXiv2024

Consistent $\mathcal{N}=4$, $D=4$ truncation of type IIB supergravity on $\textrm{S}^{1} \times \textrm{S}^{5}$

Fetching techniques from Generalised Geometry and Exceptional Field Theory, we develop a new method to identify consistent subsectors of four-dimensional gauged maximal supergravities that possess a (locally) geometric embedding in type IIB or 11D supergravity. We show that a subsector that is invariant under a structure group $\textrm{G}_\textrm{S} \subset \textrm{E}_{7(7)}$ can define a consistent truncation, even when $\textrm{G}_\textrm{S}$ is not part of the symmetry of the gauged maximal supergravity. As an illustration of the method, type IIB supergravity on $\textrm{S}^{1} \times \textrm{S}^{5}$ is shown to admit a consistent truncation to pure $\mathcal{N}=4$, $D=4$ gauged supergravity. Explicit uplift formulae are presented which provide a type IIB alternative to the M-theory embedding constructed by Cvetic, Lu and Pope $25$ years ago.

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arXiv2024

Modave Lecture notes: Introduction to Exceptional Field Theory

These notes are based on lectures given at the XIX Modave School on Mathematical Physics and present an introduction to Exceptional Field Theory. We cover the standard Kaluza-Klein reductions on tori, with applications to supergravity. We review the supergravity action of type IIA/IIB and eleven-dimensional supergravities. We motivate the appearance of the hidden symmetry groups $\mathrm{E}_{d(d)}$ through the lens of string dualities. We explore the construction and properties of $\mathrm{E}_{7(7)}$-ExFT and review other $\mathrm{E}_{d(d)}$-ExFT for $3\leq d\leq 8$, as well as double field theories. These notes conclude with some applications of ExFT to consistent truncations.

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arXiv2024

Blackening S-folds

We construct the universal AdS$_{4}$ black hole that asymptotes to the $(φ,χ)$-family of type IIB S-fold backgrounds dual to the conformal manifold of $\mathcal{N}=2$ S-fold CFT's. We present the explicit type IIB embedding of such a universal black hole for two particular asymptotics: the $\,\mathcal{N}=2\,$ S-fold with $\,\textrm{U}(2)\,$ symmetry at $\,(φ,χ)=(0,0)\,$ and the $\,\mathcal{N}=4\,$ S-fold with $\,\textrm{SO}(4)\,$ symmetry at $\,(φ,χ)=(1,0)$. As a byproduct, we also present a novel $1/16$-BPS two-parameter family of $\,\textrm{AdS}_{2} \times \textrm{M}_{8}\,$ S-fold backgrounds with $\,\textrm{M}_{8}=\mathbb{H}^{2} \times \textrm{S}^{5} \times \textrm{S}^{1}$ that features a parametrically-controlled scale separation.

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arXiv2023

$\mathcal{N}=2$ $\,\textrm{CFT}_{3}\textrm{'s}\,$ from $\,\mathcal{N} = 4\,$ gauged supergravity

We use holography and four-dimensional $\,\mathcal{N}=4\,$ gauged supergravity to collect evidence for a large class of interconnected three-dimensional $\,\mathcal{N}=2\,$ conformal field theories. On the gravity side, we construct a one-parameter family of $\,{\textrm{ISO}(3) \times \textrm{ISO}(3)}$ gaugings of half-maximal supergravity containing a rich structure of $\,\mathcal{N}=2\,$ AdS$_{4}$ solutions at fixed radius. By looking at excitations around these AdS$_{4}$ solutions, the spectrum of low lying operators in the dual $\,\mathcal{N}=2\,$ CFT$_{3}$'s is computed and further arranged into $\,\mathfrak{osp}(2|4)$ supermultiplets. Upon suitable removal of gauge redundancies, we identify the Zamolodchikov metric on the conformal manifold dual to the AdS$_{4}$ moduli space, and recover previous results in the S-fold literature. Two special points of $\,\mathcal{N}=4\,$ supersymmetry enhancement occur. While one describes an S-fold CFT$_{3}$ dual to a non-geometric type IIB twisted compactification, the string-theoretic realisation of the other, if any, is still lacking.

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arXiv2023

Holographic Evidence for Non-Supersymmetric Conformal Manifolds

We provide the first holographic evidence for the existence of a non-supersymmetric conformal manifold arising from exactly marginal but supersymmetry-breaking deformations of a superconformal three-dimensional field theory. In particular, we construct a 2-parameter non-supersymmetric deformation of a supersymmetric AdS non-geometric background in Type IIB string theory. We prove that the non-supersymmetric backgrounds are perturbatively stable and also do not suffer from various non-perturbative instabilities. Finally, we argue that diffeomorphism symmetry protects our solutions against higher-derivative string corrections.

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arXiv2022

Type IIB S-folds: flat deformations, holography and stability

We review recent progress in the study of S-folds in light of the gauge/gravity duality and the AdS swampland conjecture. S-folds correspond to non-geometric backgrounds of type IIB supergravity of the form $\,\textrm{AdS}_4 \, \times \, \textrm{S}^1 \, \times \, \mathcal{M}\,$ that involve a non-trivial $\,\textrm{SL}(2,\,\mathbb{Z})\,$ (S-duality) monodromy for the type IIB fields when moving around the $\,\textrm{S}^1$. We present four such solutions with $\,\mathcal{M}=\textrm{S}^{5}\,$ that preserve $\,\mathcal{N}=4,2,1,0\,$ supersymmetries. Via the AdS/CFT correspondence, these solutions are conjectured to describe new strongly coupled three-dimensional CFT's on a localised interface of SYM. We discuss the existence of flat deformations in the gravity side dual to marginal deformations of the conjectured S-fold CFT's. From a geometrical perspective, the flat deformations induce a monodromy $\,h\,$ on $\,\mathcal{M}\,$ and replace $\,\textrm{S}^1 \,\times\, \mathcal{M}\,$ by the so-called mapping torus $\,T(\mathcal{M})_h$. Interestingly, the flat deformations provide a controlled mechanism of supersymmetry breaking for $\,\mathcal{N} \ge 2\,$ S-folds. We present a class of such non-supersymmetric S-folds obtained by flat-deforming the $\,\mathcal{N}=4\,$ S-fold and discuss their (non-)perturbative stability.

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arXiv2021

Flat deformations of type IIB S-folds

Type IIB S-folds of the form $\textrm{AdS}_{4} \times \textrm{S}^1 \times \textrm{S}^5$ have been shown to contain axion-like deformations parameterising flat directions in the 4D scalar potential and corresponding to marginal deformations of the dual S-fold CFT's. In this note we present a group-theoretical characterisation of such flat deformations and provide a 5D interpretation thereof in terms of $\mathfrak{so}(6)$-valued duality twists inducing a class of Cremmer--Scherk--Schwarz flat gaugings in a reduction from 5D to 4D. In this manner we establish the existence of two flat deformations for the $\mathcal{N}=4$ and $\textrm{SO}(4)$ symmetric S-fold causing a symmetry breaking down to its $\textrm{U}(1)^2$ Cartan subgroup. The result is a new two-parameter family of non-supersymmetric S-folds which are perturbatively stable at the lower-dimensional supergravity level, thus providing the first examples of such type IIB backgrounds.

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arXiv2021

S-folds and holographic RG flows on the D3-brane

Type IIB S-folds of the form $\,\textrm{AdS}_{4} \times \textrm{S}^1 \times \textrm{S}^5\,$ are conjectured to correspond to new strongly coupled three-dimensional CFT's on a localised interface of $\,\textrm{SYM}_{4}\,$. In this work we construct holographic RG flows on the D3-brane that generically connect anisotropic deformations of $\,\textrm{SYM}_{4}\,$ in the UV to various S-fold $\textrm{CFT}$'s in the IR with different amounts of supersymmetry and flavour symmetries. Examples of holographic RG flows between \mbox{S-fold} CFT's are also presented. Lastly a geometric interpretation of axion deformations is provided in terms of monodromies on the internal $\,\textrm{S}^{5}\,$ when moving around the $\,\textrm{S}^{1}$. Special attention is paid to the monodromy-induced patterns of symmetry breaking as classified by the mapping torus $T_{h}(\textrm{S}^5)$.

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arXiv2021

$\mathcal{N}=2$ supersymmetric S-folds

Multi-parametric families of AdS$_{4}$ vacua with various amounts of supersymmetry and residual gauge symmetry are found in the $\,[\textrm{SO}(1,1) \times \textrm{SO}(6)] \ltimes \mathbb{R}^{12}\,$ maximal supergravity that arises from the reduction of type IIB supergravity on $\,\mathbb{R} \times \textrm{S}^5\,$. These provide natural candidates to holographically describe new strongly coupled three-dimensional CFT's which are localised on interfaces of $\,\mathcal{N}=4\,$ super-Yang--Mills theory. One such AdS$_{4}$ vacua features a symmetry enhancement to $\,\textrm{SU}(2) \times \textrm{U}(1)\,$ while preserving $\,\mathcal{N}=2\,$ supersymmetry. Fetching techniques from the $\,\textrm{E}_{7(7)}\,$ exceptional field theory, its uplift to a class of $\,\mathcal{N}=2\,$ S-folds of type IIB supergravity of the form $\,\textrm{AdS}_{4} \times \textrm{S}^{1} \times \textrm{S}^5\,$ involving S-duality twists of hyperbolic type along $\,\textrm{S}^{1}\,$ is presented.

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arXiv2019

S-folds and (non-)supersymmetric Janus solutions

The S-fold description of Janus-type solutions of type IIB supergravity is investigated. This is done by first studying a $\,\textrm{U}(1) \times \textrm{U}(1)\,$ invariant sector of the four-dimensional dyonically-gauged $\,{[\,\textrm{SO}(1,1) \times \textrm{SO}(6)\,] \ltimes \mathbb{R}^{12}}\,$ maximal supergravity that arises upon reduction of type IIB supergravity on $\,\mathbb{R} \, \times \, \textrm{S}^{5}\,$. Two AdS$_{4}$ solutions preserving $\,\textrm{SU}(3)\,$ and $\,\textrm{SO}(6)\,$ gauge symmetry together with $\,\mathcal{N}=1\,$ and $\,\mathcal{N}=0\,$ supersymmetry are found within this sector. Fetching techniques from the E$_{7(7)}$ exceptional field theory, these solutions are uplifted to ten-dimensional S-folds of type IIB Janus-type solutions of the form $\,\textrm{AdS}_{4} \times \mathbb{R} \times \textrm{M}_{5}\,$. The solutions presented here are natural candidates for the holographic duals of three-dimensional $\,\mathcal{N}=1\,$ and $\,\mathcal{N}=0\,$ interface super-Yang--Mills theories with $\,\textrm{SU}(3)\,$ and $\,\textrm{SU}(4)\,$ internal symmetry.

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