arXiv subjects

Andres Anabalon

Publications and source records attributed to Andres Anabalon.

At least 19 recordsLinked to original sources

arXiv2026

Equation of State of a Strongly Coupled Perfect Fluid with Spin from Holography

We derive the equation of state of a strongly coupled relativistic perfect fluid with finite spin in $2+1$ dimensions using holography. The dual gravitational description is provided by a spinning black hole in $AdS_4$, whose Hawking temperature, angular velocity, and Bekenstein-Hawking entropy determine the thermodynamic properties of the boundary fluid. We obtain the equation of state and analyze its local thermodynamic stability, finding a critical rotation above which the fluid becomes thermodynamically unstable providing a bound for the rotation of a strongly coupled quark gluon plasma at temperature $T$ and angular velocity $\omega$ given by $\frac{4\pi T}{\omega}> 2.77239$. Remarkably, the same gravitational solution contains a second black hole associated with a second boundary. Although this black hole is non-spinning, its dual fluid rotates and possesses a distinct, ``exotic'' equation of state. Our results provide a holographic equation of state for strongly coupled matter with finite spin and establish a direct connection between black-hole rotation, intrinsic angular momentum, and the thermodynamic stability of relativistic fluids.

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arXiv2026

Boundary-Boundary Duality on Regular Black Holes, Supersymmetric Solitons and Holographic Spinning Plasma Disks

We construct a new family of exact rotating solutions of four-dimensional Einstein--Maxwell theory with negative cosmological constant describing regular spinning AdS black holes and smooth solitons. The geometries are free of curvature singularities and admit open regions of parameter space without closed timelike curves, while supersymmetric limits correspond to causally regular horizonless configurations. A remarkable feature of these solutions is the existence of at least two codimension-one conformal boundaries. The first is Minkowski spacetime, where the expectation value of the energy--momentum tensor describes a finite spinning disk of strongly coupled conformal plasma whose edge rotates at the speed of light. The second boundary is a rotating black-hole geometry with vanishing energy--momentum tensor but non-vanishing Cotton tensor, defining a holographic theory in which the dual graviton is fixed at the boundary. We show that the energy density associated with the dual graviton exactly reproduces that of the plasma after a suitable analytic continuation and the identification of the holographic energy scale with the Lorentz factor of the rotating fluid, providing evidence for a boundary-boundary duality. Indeed, electromagnetic duality exchanges the electric and magnetic currents between the boundary supporting the graviton and that supporting the dual graviton thus providing a generalized mirror symmetry between these boundary theories. Hence, the Lorentz factor is identified with the electromagnetic dual of the renormalization scale. In an appropriate limit, the solutions reduce to the planar Reissner--Nordstr\"om--AdS black hole, whereas the supersymmetric solitons have no regular static limit.

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arXiv2026

Logarithmic corrections to the entropy of near-extremal black holes in Einstein-Gauss-Bonnet

We compute the one-loop contribution to the semiclassical partition function of near-extremal, asymptotically AdS black holes in five-dimensional Einstein-Gauss-Bonnet gravity. In the absence of an exact analytic rotating solution at finite Gauss-Bonnet coupling $\alpha$, we restrict to static, charged configurations and evaluate the contribution to $Z_{\text{1-loop}}$ arising from tensor, vector, and $U(1)$ gauge fluctuations. The analysis is based on the spectrum of a generalized Lichnerowicz operator governing linearized perturbations on the near-horizon geometry of the extremal solution, including its deformation by the coupling $\alpha$. In the canonical ensemble, the low-temperature behavior of the one-loop partition function leads to logarithmic corrections to the entropy of the form $\log(T/T_0)$, where the scale $T_0$ depends on both the fluctuation sector and the Gauss-Bonnet coupling. These corrections are controlled by the structure of zero modes of the deformed operator and their splitting at small but finite temperature. Our explicit computation yields a universal low-temperature scaling $Z_{\text{1-loop}}\sim 5 \log T$, where the coefficient arises from the combined contributions of tensor, vector, and $U(1)$ gauge modes, reflecting the corresponding counting of zero modes in each sector.

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arXiv2025

Phase Transitions and Black Hole Stability in Gauged N = 8 Supergravity

It is well known that there is a region of parameter space where all purely electric, static, dilatonic black holes are unstable within the STU models of maximal supergravity. We show that, for planar black holes, it is possible to complete the thermal phase space with AdS solitons, in such a way that the instability of the black holes signals the onset of confinement in the dual field theory. The analysis is done for the $D=4$ STU model of maximal gauged supergravity which naturally uplift to M-theory on the $S^7$.

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arXiv2025

The Geometry of Meaning: Perfect Spacetime Representations of Hierarchical Structures

We show that there is a fast algorithm that embeds hierarchical structures in three-dimensional Minkowski spacetime. The correlation of data ends up purely encoded in the causal structure. Our model relies solely on oriented token pairs -- local hierarchical signals -- with no access to global symbolic structure. We apply our method to the corpus of \textit{WordNet}. We provide a perfect embedding of the mammal sub-tree including ambiguities (more than one hierarchy per node) in such a way that the hierarchical structures get completely codified in the geometry and exactly reproduce the ground-truth. We extend this to a perfect embedding of the maximal unambiguous subset of the \textit{WordNet} with 82{,}115 noun tokens and a single hierarchy per token. We introduce a novel retrieval mechanism in which causality, not distance, governs hierarchical access. Our results seem to indicate that all discrete data has a perfect geometrical representation that is three-dimensional. The resulting embeddings are nearly conformally invariant, indicating deep connections with general relativity and field theory. These results suggest that concepts, categories, and their interrelations, namely hierarchical meaning itself, is geometric.

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arXiv2024

Plasma-Plasma Third Order Phase Transition from type IIB Supergravity

We show that the planar, charged black hole in AdS, dual to the strongly coupled Quark-Gluon Plasma thermal state of large $N$, $SU(N)$, $\mathcal{N}=4$ super Yang-Mills at finite chemical potential undergoes a third-order phase transition in the grand canonical ensemble to a hairy black hole of type IIB supergravity. The hairy phase is another strongly coupled fluid with a conformal equation of state and can be interpreted as another kind of Quark-Gluon plasma. This new Quark-Gluon plasma has less entropy and, therefore, seems to characterize some form of smooth hadronization. The locus of the transition in terms of the "Baryon" chemical potential, $μ$, and the temperature, $T$, is $μ=2πT$.

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arXiv2024

Rotating and accelerating AdS black holes in Einstein-Gauss-Bonnet Gravity

We present new, exact, rotating and accelerating solutions within the framework of five-dimensional Einstein-Gauss-Bonnet theory at the Chern-Simons point. The rotating solutions describe black holes characterized by a single rotation parameter, a mass parameter, and two extra integration constants that can be interpreted as hairs of a gravitational nature. It is noteworthy that the rotation cannot be removed by a large diffeomorphism. We also extend our procedure to dimension seven, providing a new rotating black hole solution with two rotation parameters pertaining to cubic Lovelock theory with a unique vacuum.

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arXiv2021

Supersymmetric solitons and a degeneracy of solutions in AdS/CFT

We study Lorentzian supersymmetric configurations in $D=4$ and $D=5$ gauged $\mathcal{N}=2$ supergravity. We show that there are smooth $1/2$ BPS solutions which are asymptotically AdS$_{4}$ and AdS$_{5}$ with a planar boundary, a compact spacelike direction and with a Wilson line on that circle. There are solitons where the $S^{1}$ shrinks smoothly to zero in the interior, with a magnetic flux through the circle determined by the Wilson line, which are AdS analogues of the Melvin fluxtube. There is also a solution with a constant gauge field, which is pure AdS. Both solutions preserve half of the supersymmetries at a special value of the Wilson line. There is a phase transition between these two saddle-points as a function of the Wilson line precisely at the supersymmetric point. Thus, the supersymmetric solutions are degenerate, at least at the supergravity level. We extend this discussion to one of the Romans solutions in four dimensions when the Euclidean boundary is $S^{1}\timesΣ_{g}$ where $Σ_{g}$ is a Riemann surface with genus $g > 0$. We speculate that the supersymmetric state of the CFT on the boundary is dual to a superposition of the two degenerate geometries.

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arXiv2021

New non-extremal and BPS hairy black holes in gauged $\,\mathcal{N}=2\,$ and $\,\mathcal{N}=8\,$ supergravity

In this article we study a family of four-dimensional, $\mathcal{N}=2$ supergravity theories that interpolates between all the single dilaton truncations of the $\mathrm{SO}(8)$ gauged $\mathcal{N}=8$ supergravity. In this infinitely many theories characterized by two real numbers -- the interpolation parameter and the dyonic "angle" of the gauging -- we construct non-extremal electrically or magnetically charged black hole solutions and their supersymmetric limits. All the supersymmetric black holes have non-singular horizons with spherical, hyperbolic or planar topology. Some of these supersymmetric and non-extremal black holes are new examples in the $\mathcal{N}=8$ theory that do not belong to the STU model. We compute the asymptotic charges, thermodynamics and boundary conditions of these black holes and show that all of them, except one, introduce a triple trace deformation in the dual theory.

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arXiv2020

Supersymmetric traversable wormholes

We study traversable wormhole solutions in pure gauged $N\!=\!2$ supergravity with and without electromagnetic fields, which are locally isometric under $\mathrm{SO}(2,1)\!\times\!\mathrm{SO}(1,1)$. The model allows for 1/2-BPS wormhole solutions whose corresponding globally defined Killing spinors are presented. A non-contractible cycle can be obtained by compactifying one of the coordinates which leaves the residual supersymmetry unaffected, the isometry group is now globally $\mathrm{SO}(2,1)\!\times\!\mathrm{SO}(2)$. The wormholes connect two asymptotic, locally $\mathrm{AdS}_4$ regions and depend on certain electric and magnetic charge parameters and, implicitly, on the range of the compact coordinate around the throat. We provide an analysis of the boundary of the spacetime and show that it can be either disconnected or not, depending on the values of the parameters in the metric. Finally, we show how that these space-times avoid a topological censorship theorem.

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arXiv2019

Phase transitions of neutral planar hairy AdS black holes

We investigate the phase diagram of a general class of $4$-dimensional exact regular hairy planar black holes. For some particular values of the parameters in the moduli potential, these solutions can be embedded in $ω$-deformed $\mathcal{N}=8$ gauged supergravity. We construct the hairy soliton that is the ground state of the theory and show that there exist first order phase transitions.

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arXiv2019

Thermodynamics of Charged, Rotating, and Accelerating Black Holes

We show how to obtain a consistent thermodynamic description of accelerating asymptotically AdS black holes, extending our previous results by including charge and rotation. We find that the key ingredient of consistent thermodynamics is to ensure that the system is not over-constrained by including the possibility of varying the `string' tensions that are responsible for the acceleration of the black hole, yielding a first law of full cohomogeneity. The first law assumes the standard form, with the entropy given by one quarter of the horizon area and other quantities identified by standard methods. In particular we compute the mass in two independent ways: through a Euclidean action calculation and by the method of conformal completion. The ambiguity in the choice of the normalization of the timelike Killing vector can be fixed by explicit coordinate transformation (in the case of rotation) to the standard AdS form or by holographic methods (in the case of charge). This resolves a long-standing problem of formulating the thermodynamics of accelerating black holes, opening the way to detailed studies of their phase behaviour.

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arXiv2019

Fully resonant scalars on asymptotically AdS wormholes

In this work we show the existence of asymptotically AdS wormhole geometries where the scalar probe has an equispaced, fully resonant spectrum, as that of a scalar on AdS spacetime, and explore its dynamics when non-linearities are included. The spacetime is a solution of Einstein-Gauss-Bonnet theory with a single maximally symmetric vacuum. Introducing a non-minimal coupling between the scalar probe and the Ricci scalar remarkably leads to a fully resonant spectrum for a scalar field fulfilling reflective boundary conditions at both infinities. Applying perturbative methods, which are particularly useful for unveiling the dynamics at time scales of order $\varepsilon^{-2}$ (where $\varepsilon$ characterizes the amplitude of the initial perturbation), we observe both direct and inverse energy cascades between modes. This motivates us to explore the energy returns in the case in which the dynamics is dominated by a single mode. We find numerical and perturbative evidence that near exact returns do exist in this regime. We also provide some comments on the fully backreracting case and provide a proof of the universality of the weakly non-linear dynamics around AdS, in the context of Lovelock theories with generic couplings, up to times of order $\varepsilon^{-2}$.

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arXiv2019

Kerr-NUT-de Sitter as an Inhomogeneous Non-Singular Bouncing Cosmology

We present exact non-singular bounce solutions of general relativity in the presence of a positive cosmological constant and an electromagnetic field, without any exotic matter. The solutions are distinguished by being spatially inhomogeneous in one direction, while they can also contain non-trivial electromagnetic field lines. The inhomogeneity may be substantial, for instance, there can be one bounce in one region of the universe and two bounces elsewhere. Since the bounces are followed by a phase of accelerated expansion, the metrics described here also permit the study of (geodesically complete) models of inflation with inhomogeneous initial conditions. Our solutions admit two Killing vectors and may be re-interpreted as the pathology-free interior regions of Kerr-de Sitter black holes with non-trivial NUT charge. Remarkably enough, within this cosmological context, the NUT parameter does not introduce any string singularity nor closed timelike curves but renders the geometry everywhere regular, eliminating the big bang singularity by means of a bounce.

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arXiv2019

Scalar field quasinormal modes on asymptotically locally flat rotating black holes in three dimensions

The pure quadratic term of New Massive Gravity in three dimensions admits asymptotically locally flat, rotating black holes. These black holes are characterized by their mass and angular momentum, as well as by a hair of gravitational origin. As in the Myers-Perry solution in dimensions greater than five, there is no upper bound on the angular momentum. We show that, remarkably, the equation for a massless scalar field on this background can be solved in an analytic manner and that the quasinormal frequencies can be found in a closed form. The spectrum is obtained requiring ingoing boundary conditions at the horizon and an asymptotic behavior at spatial infinity that provides a well-defined action principle for the scalar probe. As the angular momentum of the black hole approaches zero, the imaginary part of the quasinormal frequencies tends to minus infinity, migrating to the north pole of the Riemann Sphere and providing infinitely damped modes of high frequency. We show that this is consistent with the fact that the static black hole within this family does not admit quasinormal modes for a massless scalar probe.

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arXiv2018

Holographic Thermodynamics of Accelerating Black Holes

We present a careful study of accelerating black holes in anti-de Sitter spacetime, formulating the thermodynamics and resolving discrepancies that have appeared in previous investigations of the topic. We compute the dual stress-energy tensor for the spacetime and identify the energy density associated with a static observer at infinity. The dual energy-momentum tensor can be written as a three-dimensional perfect fluid plus a non-hydrodynamic contribution with a universal coefficient which is given in gauge theory variables. We demonstrate that both the holographic computation and the method of conformal completion yield the same result for the mass. We compare to previous work on black funnels and droplets, showing that the boundary region can be endowed with non-compact geometry, and comment on this novel holographic dual geometry.

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arXiv2018

Four-dimensional Traversable Wormholes and Bouncing Cosmologies in Vacuum

In this letter we point out the existence of solutions to General Relativity with a negative cosmological constant in four dimensions, which contain solitons as well as traversable wormholes. The latter connect two asymptotically locally AdS$_{4}$ spacetimes. At every constant value of the radial coordinate the spacetime is a spacelike warped AdS$_{3}$. We compute the dual energy momentum tensor at each boundary showing that it yields different results. We also show that these vacuum wormholes can have more than one throat and that they are indeed traversable by computing the time it takes for a light signal to go from one boundary to the other, as seen by a geodesic observer. We generalize the wormholes to include rotation and charge. When the cosmological constant is positive we find a cosmology that is everywhere regular, has either one or two bounces and that for late and early times matches the Friedmann-Lema\^ıtre-Robertson-Walker metric with spherical topology.

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arXiv2018

Hairy Black Holes and Duality in an Extended Supergravity Model

We consider a $D=4$, $\mathcal{N}=2$ gauged supergravity with an electromagentic Fayet-Iliopoulos term. We restrict to the uncharged, single dilaton consistent truncation and point out that the bulk Lagrangian is self-dual under electromagnetic duality. Within this truncation, we construct two families of exact hairy black hole solutions, which are asymptotically $AdS_4$. When a duality transformation is applied on these solutions, they are mapped to two other inequivalent families of hairy black hole solutions. The mixed boundary conditions of the scalar field correspond to adding a triple-trace operator to the dual field theory action. We also show that the this truncation contains all the consistent single dilaton truncations of gauged $\mathcal{N}=8$ supergravity with a possible $ω$-deformation.

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