arXiv subjects

Adolfo Guarino

Publications and source records attributed to Adolfo Guarino.

At least 19 recordsLinked to original sources

arXiv2026

On the branes behind scale-separated AdS$_{3}$ flux vacua

We investigate the brane origin of supersymmetric and scale-separated AdS$_3$ flux vacua arising in a class of type IIB orientifold reductions with G$_2$-structure. First, using the effective three-dimensional supergravity together with explicit uplift formulae, we trace back the $F_{(7)}$ and $F_{(3)}$ fluxes responsible for scale separation and identify the type IIB background that is probed by the corresponding D1- and D5-branes. Second, by restoring such D1- and D5-branes, we obtain a type IIB solution that interpolates between the previous background in the asymptotic region and the scale-separated AdS$_3$ flux vacua in the near-horizon region. Third, by working directly in ten dimensions, we construct a codimension-one D1-D5-KK5 intersection whose near-horizon region realises the scale-separated AdS$_3$ flux vacua. Our results provide a higher-dimensional interpretation of these flux vacua in terms of (smeared) brane configurations.

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arXiv2025

Taxonomy of type II orientifold flux vacua in 3D

We complete the study initiated in \cite{Arboleya:2024vnp} and investigate three-dimensional (3D) flux vacua of type II orientifold reductions on twisted tori that include a single type of spacetime-filling O$p$-plane with $\,p=2,\ldots,9$. Restricting to $\textrm{SO}(3)$-invariant setups -- also known as RSTU-models -- and setting axions to zero, we exhaustively chart the landscape of 3D orientifold flux vacua. It consists of $\,56\,$ inequivalent multi-parametric families of AdS$_3$ and Mkw$_3$ flux vacua, all of them without negative masses in the spectrum of scalar fluctuations. Performing T-dualities, all the inequivalent vacua can be found in type IIB with either O9-, O5- or O3-planes. We show that: $i)\,$ type IIB with O$9$ fails to stabilise the volume of the internal space. $ii)\,$ type IIB with O5 realises the only cases of scale-separated AdS$_{3}$ vacua. $iii)\,$ type IIB with O$3$ provides only Mkw$_{3}$ vacua exhibiting a rich variety of supersymmetry-breaking patterns. Assuming that some mechanism (possibly non-perturbative) fixes the unstabilised modulus in type IIB with O$9$, we re-examine the possibility of achieving a weakly-coupled and scale-separated regime.

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arXiv2025

Type II orientifold flux vacua in 3D

We initiate a systematic study of type II orientifold flux vacua in three dimensions including gauge and metric fluxes, O-planes and D-branes. We derive simple flux models (we dub them RSTU-models) that admit a description in terms of gauged supergravities with half-maximal $\,\mathcal{N}=8\,$ supersymmetry in three dimensions. As a landscape appetizer, we present various multi-parametric families of supersymmetric and non-supersymmetric AdS$_{3}$ and Mkw$_{3}$ vacua. Remarkably, negative masses turn out to be always absent in the spectrum of scalar fluctuations, thus making all the vacua perturbatively stable within half-maximal supergravity. We provide examples of non-supersymmetric type IIB AdS$_{3}$ flux vacua which feature parametrically-controlled scale separation and come along with integer-valued conformal dimensions of the would-be dual CFT$_{2}$ operators. We also comment on the implications of our results in light of the Swampland Program.

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arXiv2025

On type IIB AdS$_{3}$ flux vacua with scale separation and integer conformal dimensions

We review recent progress in constructing type IIB AdS$_{3}$ flux vacua that exhibit parametrically-controlled scale separation and come along with integer-valued conformal dimensions for the would-be dual CFT$_{2}$ operators. We comment on the anisotropic nature of the associated internal spaces, as well as on the existence of polynomial shift symmetries underlying the mass spectra. We conclude by outlining open questions and potential directions for future research, partially inspired by the Swampland program.

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arXiv2025

Open strings in type IIB AdS$_3$ flux vacua

The role of open strings is investigated in the context of AdS$_{3}$ flux vacua arising from type IIB orientifold reductions. On the one hand, contrary to expectations, the perturbative stability of certain recently found non-supersymmetric AdS$_{3}$ flux vacua is shown to be robust under fluctuations of the open-string moduli. On the other hand, a wealth of new perturbatively stable AdS$_{3}$ flux vacua appears as a consequence of the non-trivial dynamics of open-string moduli. We also comment on the issue of scale separation in these AdS$_{3}$ flux vacua.

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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

Euclidean flows, solitons and wormholes in AdS from M-theory

Multi-parametric families of non-supersymmetric EAdS$_{4}$ flows as well as asymptotically EAdS$_{4}$ solitons and wormholes are constructed within the four-dimensional $\textrm{SO}(8)$ gauged supergravity that describes the compactification of M-theory on $\textrm{S}^{7}$. More concretely, the solutions are found within the so-called STU-model that describes the $\textrm{U}(1)^4$ invariant sector of the theory. The on-shell action and gravitational free energy are computed for the regular solutions, the latter being zero for the wormholes irrespective of supersymmetry. There are special loci in parameter space yielding solutions with enhanced (super)symmetry. Examples include a supersymmetric EAdS$_{4}$ flow with $\textrm{SO}(4) \times \textrm{SO}(4)$ symmetry dual to a specific real mass deformation of ABJM on S$^{3}$ as well as a non-supersymmetric wormhole with $\textrm{SU}(3) \times \textrm{U}(1)^2$ symmetry. Uplift formulae for these and other examples to Euclidean solutions of eleven-dimensional supergravity are presented and their complex nature discussed.

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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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arXiv2024

Janus and Hades in M-theory

Multi-parametric and analytic families of four-dimensional $\,\textrm{AdS}_{3} \times \mathbb{R}\,$ (Janus) and $\,\textrm{AdS}_{3} \,\times\, \mathbb{R}^{+}$ (Hades) solutions are constructed in the SO(8) gauged supergravity that arises from the consistent reduction of eleven-dimensional supergravity on $\,\textrm{S}^7\,$. The solutions are generically non-supersymmetric, involve non-trivial running scalars and preserve a $\,\textrm{U}(1)^4\,$ symmetry. Different patterns of (super) symmetry enhancement occur upon suitable adjustment of the free parameters which further control the boundary conditions of the running scalars. We concentrate on the non-supersymmetric Janus and Hades solutions with $\,\textrm{SU}(3) \times \textrm{U}(1)^2\,$ symmetry and provide their higher-dimensional description in terms of M-theory fluxes and membranes. Special attention is paid to a class of such Hades solutions dubbed "ridge flows" which resemble dielectric rotations of Coulomb branch flows previously investigated in the literature.

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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

S-folds and $AdS_{3}$ flows from the D3-brane

We investigate supersymmetric flows in type IIB supergravity that preserve an $SO(2,2)$ space-time symmetry and asymptote to $AdS_{5} \times S^5$ at both endpoints. The flows are constructed as Janus-type $\mathbb{R} \times AdS_{3}$ BPS domain-walls in the effective four-dimensional $[SO(1,1)\times{S}O(6)]\ltimes\mathbb{R}^{12}$ gauged maximal supergravity describing the massless sector of type IIB supergravity compactified on $S^1 \times S^{5}$. The compactification includes an S-duality hyperbolic twist along the $S^1$ which, when combined with an appropriate choice of boundary conditions for the running scalars, generates special flows that develop an S-fold regime at their core, thus enhancing the space-time symmetry there to $SO(2,3)$. Via the AdS/CFT correspondence, the flows constructed here are conjectured to describe conformal interfaces in a circle compactification of $\mathcal{N}=4$ $\textrm{SYM}_{4}$.

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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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arXiv2021

Stable non-supersymmetric Anti-de Sitter vacua of massive IIA supergravity

Stable non-supersymmetric Anti-de Sitter (AdS) vacua of string theory are widely believed not to exist. In this letter, we analytically compute the full bosonic Kaluza-Klein spectrum around the ${\rm G_2}$-invariant non-supersymmetric $\textrm{AdS}_4$ solution of massive IIA supergravity, and show that it is perturbatively stable. We also provide evidence that six other non-supersymmetric $\textrm{AdS}_4$ solutions of massive IIA supergravity are perturbatively stable. Since previous studies have indicated that these AdS vacua may also be non-perturbatively stable, our findings pose a challenge to the Swampland Conjecture.

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arXiv2020

Brane-jet stability of non-supersymmetric AdS vacua

We classify the non-supersymmetric, and perturbatively stable within $D=4$, AdS vacua of maximal $D=4$ supergravity with a dyonic ISO(7) gauging in a large sector of the supergravity. Seven such vacua are established within this sector, all of them giving rise to non-supersymmetric $\textrm{AdS}_{4} \times \textrm{S}^{6}$ type IIA backgrounds with and without non-trivial warpings and with internal fluxes. Then, we analyse the dynamics of various probe D$p$-branes in these backgrounds searching for potential brane-jet instabilities. In all these cases, such instabilities are absent. Finally, an alternative decay channel through tunnelling is investigated, focusing on one of the seven backgrounds. We do not find instabilities either, but the analysis remains inconclusive.

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