arXiv subjects

Alberto Zaffaroni

Publications and source records attributed to Alberto Zaffaroni.

At least 19 recordsLinked to original sources

arXiv2025

Fortuity in ABJM

We study $1/12$-BPS and $1/16$-BPS cohomologies and the fortuitous mechanism in ABJM theory. We first establish the existence of fortuitous states in the $N=1$ theory, where the theory is abelian and trace relations are extreme. We then provide explicit constructions of fortuitous states at $N=2$. We find fortuitous states both at weak coupling, in direct parallel to what has been done in $\mathcal{N}=4$ SYM, but we also find additional fortuitous states at $k=2$, which is in the strongly coupled regime. The extra fortuitous states that appear at $k=2$ are in non-trivial monopole sectors. A striking distinction from $\mathcal{N}=4$ SYM is that the fortuitous states appear at much smaller quantum numbers, making them easier to find. Along the way, we formulate a non-renormalization conjecture for cohomologies in ABJM.

hep-th↗

arXiv2025

Patch-wise localization with Chern-Simons forms in five dimensional supergravity

In this paper, using equivariant localization for foliations, we compute the on-shell action of a general class of supersymmetric solutions of five-dimensional gauged supergravity with vector multiplets. Unlike previous literature, we also allow for a non-trivial topology for the space-time as well as for the gauge fields. In practice, we achieve this by covering the spacetime manifold with patches and localizing in each patch. We derive a general formula for the on-shell action that depends on topological data only and can be used without a detailed knowledge of the solution. Our final result is relevant for the physically interesting examples of multi-center black holes, black rings and black lenses, topological solitons and Euclidean black saddles. We also show how to connect the topological data with the thermodynamic data: electrostatic potential, the magnetic fluxes and the possible flat connections of the solutions. Our formula for the on-shell action is derived in the context of gauged supergravity, but it is straightforward to take the ungauged limit. Thus, we reproduce known results for a large class of explicit asymptotically flat supersymmetric solutions, and we provide predictions for AdS solutions still to be found.

hep-th↗

arXiv2025

$\mathcal{I}$-Extremization for AdS$_4$ Black Holes: Master Volume, Free Energy, and Baryonic Charges

In a previous paper, we proposed an entropy function for AdS$_4$ BPS black holes in M-theory with general magnetic charges, resolving a long-standing puzzle about baryonic charges in three-dimensional holography and offering a prediction for the large-$N$ limit of several partition functions whose saddle points have yet to be found. The entropy function is constructed from the master volume of the internal manifold. In this paper, we prove that the entropy of a general class of black holes based on toric geometry can indeed be reformulated as an $\mathcal{I}$-extremization problem, and we provide a set of examples. As an aside, we also simplify existing proofs of the equivalence between $a$-, $c$-, and $F$-extremizations and their gravitational duals.

hep-th↗

arXiv2025

$\mathcal{I}$-extremization with baryonic charges

We propose an entropy function for AdS$_4$ BPS black holes in M-theory with general magnetic charges, resolving in particular a long-standing puzzle about baryonic charges. The entropy function is constructed from a gravitational block defined solely in terms of topological data of the internal manifold. We show that the entropy of twisted black holes can always be reformulated as an $\mathcal{I}$-extremization problem -- even in cases where existing large-$N$ field theory computations fail to provide an answer. Furthermore, we correctly reproduce the entropy for a class of known black holes with purely baryonic magnetic charges. Our results offer both a conjecture for the general gravitational block for AdS$_4$ black holes in M-theory and a prediction for the large-$N$ limit of several partition functions whose saddle points have yet to be found.

hep-th↗

arXiv2025

Equivariant localization in supergravity in odd dimensions

We discuss a localization formula for certain integrals on odd-dimensional manifolds with boundaries, equipped with a Killing vector, and employ this to localize the regularised on-shell action of a large class of supersymmetric solutions of five dimensional minimal gauged supergravity. Specifically, we consider asymptotically AdS_5 solutions in the time-like class, in which the transverse K\"ahler foliation is assumed to be toric. We find that the background subtraction regularization method leads to an intriguing formula for the on-shell action, in terms of an analytic continuation of the Martelli-Sparks-Yau Sasakian volume. In particular, we show that the regularised on-shell action is a function of the toric data of an effective compact five-dimensional manifold, as well as of the supersymmetric Killing vector, outside the corresponding dual cone. As our main example we provide a derivation of the well-known entropy function of supersymmetric and rotating black holes in AdS_5, using only topological data.

hep-th↗

arXiv2024

Microstates of accelerating and supersymmetric AdS$_4$ black holes from the spindle index

We provide a first principles derivation of the microscopic entropy of a very general class of supersymmetric, rotating and accelerating black holes in AdS$_4$. This is achieved by analysing the large-$N$ limit of the spindle index and completes the construction of the first example of a holographic duality involving supersymmetric field theories defined on orbifolds with conical singularities.

hep-th↗

arXiv2023

Equivariant volume extremization and holography

In a previous paper two of us (D.M. and A.Z.) proposed that a vast class of gravitational extremization problems in holography can be formulated in terms of the equivariant volume of the internal geometry, or of the cone over it. We substantiate this claim by analysing supergravity solutions corresponding to branes partially or totally wrapped on a four-dimensional orbifold, both in M-theory as well as in type II supergravities. We show that our approach recovers the relevant gravitational central charges/free energies of several known supergravity solutions and can be used to compute these also for solutions that are not known explicitly. Moreover, we demonstrate the validity of previously conjectured gravitational block formulas for M5 and D4 branes. In the case of M5 branes we make contact with a recent approach based on localization of equivariant forms, constructed with Killing spinor bilinears.

hep-th↗

arXiv2023

Equivariant localization and holography

We discuss the theory of equivariant localization focussing on applications relevant for holography. We consider geometries comprising compact and non-compact toric orbifolds, as well as more general non-compact toric Calabi-Yau singularities. A key object in our constructions is the equivariant volume, for which we describe two methods of evaluation: the Berline-Vergne fixed-point formula and the Molien-Weyl formula, supplemented by the Jeffrey-Kirwan prescription. We present two applications in supersymmetric field theories. Firstly, we describe a method for integrating the anomaly polynomial of SCFTs on compact toric orbifolds. Secondly, we discuss equivariant orbifold indices that are expected to play a key role in the computation of supersymmetric partition functions. In the context of supergravity, we propose that the equivariant volume can be used to characterise universally the geometry of a large class of supersymmetric solutions. As an illustration, we employ equivariant localization to prove the factorization in gravitational blocks of various supergravity free energies, recovering previous results as well as obtaining generalizations.

hep-th↗

arXiv2022

The large $N$ limit of topologically twisted indices: a direct approach

We study the large $N$ limit of the refined topologically twisted index of three-dimensional $\mathcal{N} = 2$ gauge theories with a holographic dual, which is relevant for counting the number of microstates of rotating, magnetically charged and twisted AdS$_4$ black holes. As a difference with previous computations, we perform a direct saddle point analysis of the relevant matrix model. Among other things we explicitly identify the distribution of gauge magnetic fluxes that contributes at large $N$. The index exhibits a large $N$ factorized form in agreement with the supergravity expectations based on gravitational blocks and correctly reproduces the entropy of magnetically charged rotating AdS$_4 \times S^7$ black holes.

hep-th↗

arXiv2021

The joy of factorization at large $N$: five-dimensional indices and AdS black holes

We discuss the large $N$ factorization properties of five-dimensional supersymmetric partition functions for CFT with a holographic dual. We consider partition functions on manifolds of the form $\mathcal{M}= \mathcal{M}_3 \times S^2_ε$, where $ε$ is an equivariant parameter for rotation. We show that, when $\mathcal{M}_3$ is a squashed three-sphere, the large $N$ partition functions can be obtained by gluing elementary blocks associated with simple physical quantities. The same is true for various observables of the theories on $\mathcal{M}_3=Σ_\mathfrak{g} \times S^1$, where $Σ_\mathfrak{g}$ is a Riemann surface of genus $\mathfrak{g}$, and, with a natural assumption on the form of the saddle point, also for the partition function, corresponding to either the topologically twisted index or a mixed one. This generalizes results in three and four dimensions and correctly reproduces the entropy of known black objects in AdS$_6 \times_{w} S^4$ and AdS$_7\times S^4$. We also provide the supersymmetric background and explicitly perform localization for the mixed index on $Σ_\mathfrak{g} \times S^1 \times S^2_ε$, filling a gap in the literature.

hep-th↗

arXiv2021

Rotating multi-charge spindles and their microstates

Some AdS$_3 \times M_7$ type IIB vacua have been recently proposed to arise from D3-branes wrapped on a spindle, a sphere with conical singularities at the poles. We explicitly construct a generalization of these solutions corresponding to a class of electrically charged and rotating supersymmetric black strings in AdS$_5 \times S^5$ with general magnetic fluxes on the spindle. We then perform a counting of their microstates using the charged Cardy formula. To this purpose, we derive the general form of the anomaly polynomial of the dual $\mathcal{N} = (0 , 2)$ CFT in two dimensions and we show that it can be obtained via a simple gluing procedure.

hep-th↗

arXiv2021

Universal AdS black holes in theories with sixteen supercharges and their microstates

We provide a universal microscopic counting for the microstates of the asymptotically AdS black holes and black strings that arise as solutions of the half-maximal gauged supergravity in four and five dimensions. These solutions can be embedded in all M-theory and type II string backgrounds with an AdS vacuum and sixteen supercharges and provide an infinite set of examples dual to $\mathcal{N}=2$ and $\mathcal{N}=4$ conformal field theories in four and three dimensions, respectively. The counting is universal and it is performed by either studying the large $N$ limit of the relevant supersymmetric index of the dual field theory or by using the charged Cardy formula.

hep-th↗

arXiv2021

Anomalies, Black strings and the charged Cardy formula

We derive the general anomaly polynomial for a class of two-dimensional CFTs arising as twisted compactifications of a higher-dimensional theory on compact manifolds $\mathcal{M}_d$, including the contribution of the isometries of $\mathcal{M}_d$. We then use the result to perform a counting of microstates for electrically charged and rotating supersymmetric black strings in AdS$_5\times S^5$ and AdS$_7\times S^4$ with horizon topology BTZ$ \ltimes S^2$ and BTZ$ \ltimes S^2 \times Σ_\mathfrak{g}$, respectively, where $Σ_\mathfrak{g}$ is a Riemann surface. We explicitly construct the latter class of solutions by uplifting a class of four-dimensional rotating black holes. We provide a microscopic explanation of the entropy of such black holes by using a charged version of the Cardy formula.

hep-th↗

arXiv2021

Microstates of rotating AdS$_5$ strings

We provide a general formula for the refined topologically twisted index of $\mathcal{N}=1$ gauge theories living on the world-volume of D3-branes at conical Calabi-Yau singularities in the Cardy limit. The index is defined as the partition function on $T^2 \times S^2_ω$, with a partial topological twist and a $Ω$-deformation along $S^2$, in the presence of background magnetic fluxes and fugacities for the global symmetries and can be used to study the properties of a class of BPS black strings. To this purpose, we find rotating domain-wall solutions of five-dimensional gauged supergravity interpolating between AdS$_5$ and a near horizon region consisting of a warped fibration of BTZ over a sphere. We explicitly construct rotating domain-walls that can be embedded in AdS$_5 \times S^5$ by uplifting a class of four-dimensional rotating black holes. We then provide a microscopic explanation of the entropy of such black holes by using the refined topologically twisted index of $\mathcal{N}=4$ super Yang-Mills.

hep-th↗

arXiv2021

Gluing gravitational blocks for AdS black holes

We provide a unifying entropy functional and an extremization principle for black holes and black strings in AdS$_4\times S^7$ and AdS$_5\times S^5$ with arbitrary rotation and generic electric and magnetic charges. This is done by gluing gravitational blocks, basic building blocks that are directly inspired by the holomorphic blocks appearing in the factorization of supersymmetric partition functions in three and four dimensions. We also provide an explicit realization of the attractor mechanism by identifying the values of the scalar fields at the horizon with the critical points of the entropy functional. We give examples based on dyonic rotating black holes with a twist in AdS$_4\times S^7$, rotating black strings in AdS$_5\times S^5$, dyonic Kerr-Newman black holes in AdS$_4\times S^7$ and Kerr-Newman black holes in AdS$_5\times S^5$. In particular, our entropy functional extends existing results by adding rotation to the twisted black holes in AdS$_4$ and by adding flavor magnetic charges for the Kerr-Newman black holes in AdS$_4$. We also discuss generalizations to higher-dimensional black objects.

hep-th↗

arXiv2020

Lectures on AdS Black Holes, Holography and Localization

In these lectures I review some recent progresses in counting the number of microstates of AdS supersymmetric black holes in dimensions equal or greater than four using holography. The counting is obtained by applying localization and matrix model techniques to the dual field theory. I cover in details the case of dyonic AdS$_4$ black holes, corresponding to a twisted compactification of the dual field theory, and I discuss the state of the art for rotating AdS$_5$ black holes.

hep-th↗

arXiv2020

Superconformal indices at large $N$ and the entropy of AdS$_5$ $\times$ SE$_5$ black holes

The large $N$ limit of the four-dimensional superconformal index was computed and successfully compared to the entropy of a class of AdS$_5$ black holes only in the particular case of equal angular momenta. Using the Bethe Ansatz formulation, we compute the index at large $N$ with arbitrary chemical potentials for all charges and angular momenta, for general $\mathcal{N}=1$ four-dimensional conformal theories with a holographic dual. We conjecture and bring some evidence that a particular universal contribution to the sum over Bethe vacua dominates the index at large $N$. For $\mathcal{N}=4$ SYM, this contribution correctly leads to the entropy of BPS Kerr-Newman black holes in AdS$_5 \times S^5$ for arbitrary values of the conserved charges, thus completing the microscopic derivation of their microstates. We also consider theories dual to AdS$_5 \times \mathrm{SE}_5$, where SE$_5$ is a Sasaki-Einstein manifold. We first check our results against the so-called universal black hole. We then explicitly construct the near-horizon geometry of BPS Kerr-Newman black holes in AdS$_5 \times T^{1,1}$, charged under the baryonic symmetry of the conifold theory and with equal angular momenta. We compute the entropy of these black holes using the attractor mechanism and find complete agreement with the field theory predictions.

hep-th↗

arXiv2019

Geometry of $\mathcal{I}$-extremization and black holes microstates

The entropy of a class of asymptotically AdS$_4$ magnetically charged BPS black holes can be obtained by extremizing the topologically twisted index of the dual three-dimensional field theory. This principle is known as $\mathcal{I}$-extremization. A gravitational dual of $\mathcal{I}$-extremization for a class of theories obtained by twisted compactifications of M2-branes living at a Calabi-Yau four-fold has been recently proposed. In this paper we investigate the relation between the two extremization principles. We show that the two extremization procedures are equivalent for theories without baryonic symmetries, which include ABJM and the theory dual to the non-toric Sasaki-Einstein manifold $V^{5,2}$. We then consider a class of quivers dual to M2-branes at toric Calabi-Yau four-folds for which the $\mathcal{I}$-functional can be computed in the large $N$ limit, and depends on three mesonic fluxes. We propose a gravitational dual for this construction, that we call mesonic twist, and we show that the gravitational extremization problem and $\mathcal{I}$-extremization are equivalent. We comment on more general cases.

hep-th↗