arXiv subjects

Leopoldo A. Pando Zayas

Publications and source records attributed to Leopoldo A. Pando Zayas.

At least 19 recordsLinked to original sources

arXiv2026

One-loop Corrected Holographic Shear Viscosity to Entropy Density Ratio at Low Temperatures

Near-extremal black holes contain infrared-enhanced quantum fluctuations in their near-horizon near-AdS$_2$ throat, governed in part by Schwarzian modes. We study the effect of these fluctuations on the zero-frequency stress-tensor response of a near-extremal asymptotically AdS$_4$ Reissner--Nordström black brane whose transverse directions are regulated by a finite toroidal quotient. Working directly in four dimensions, we compute the leading correction in the weakly coupled Schwarzian regime $T_q\ll T\ll r_0/L^2$. At one loop, the shear perturbation couples to the $n=2$ would-be zero mode and produces a correction proportional to $T_q/T$. Together with the logarithmic correction to the entropy, this yields a finite-volume correction to $η/s$. Our calculation provides a direct four-dimensional benchmark, complementary to exact two-dimensional treatments, while keeping the asymptotic AdS$_4$ source explicit.

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arXiv2026

The giant graviton expansion in AdS$_5\times$SE$_5$

We study giant graviton-like D3-branes as probe configurations in type IIB supergravity backgrounds AdS$_5\times$SE$_5$, with emphasis on the structure of the five-dimensional Sasaki-Einstein manifolds SE$_5$. These configurations wrap supersymmetric three-cycles in SE$_5$ and rotate at the speed of light along the Reeb direction. We formulate the general problem in terms of the transverse Kähler potential and show that configurations carrying maximal angular momentum can be described by loci where the transverse Kähler potential diverges in suitably chosen coordinates. We quantize a particular set of excitations, similar to those considered in the AdS$_5\times S^5$ case, and show that they are governed by a Fock-Darwin problem with a conical deficit, which generalizes the Landau problem obtained for $S^5$. Succinctly, the information about the geometry of SE$_5$ is encoded in the form of the external potential and the conical deficit. We compute a protected contribution to the superconformal index arising from quantized fluctuations of supersymmetric giant graviton configurations. For the explicit case of AdS$_5\times T^{1,1}$, we recover the finite-$N$ protected index of the dual quiver ${\cal N}=1$ superconformal field theory in the sector captured by a non-Abelian generalization of the quantized degrees of freedom.

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arXiv2026

Low-Temperature Holographic Conductivity

We revisit holographic electrical conductivity in the regime of very low temperatures where quantum fluctuations in the throat of the near-extremal, asymptotically AdS$_4$ dual black brane are strongly coupled. We treat the fluctuations via an effective two-dimensional action capturing the effects of the Schwarzian modes at the scale $1/C$. Our main result is a non-monotonic temperature dependence: the quantum-corrected conductivity decreases as the temperature is lowered, reaches a minimum at $(CT_{\mathrm{min}}\simeq 0.023)$, and grows as $(1/\sqrt{CT})$ for $(CT\ll 1)$. We further estimate the one-loop contribution to the conductivity directly from the four-dimensional gravitational path integral and find qualitative agreement with the effective two-dimensional description in the regime $(CT\gg 1)$. We find that quantum corrections substantially modify the low-temperature behavior of the holographic conductivity in both approaches.

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arXiv2026

Low-temperature Quantum-corrected Holographic Transport with Momentum Relaxation

We determine the quantum corrections to transport arising from fluctuations of the near-AdS${}_2$ throat of near-extremal black branes in holographic models with momentum relaxation. By computing the shear viscosity and electrical conductivity at both zero and finite chemical potential, we uncover a universal low-temperature enhancement of transport generated by Schwarzian quantum fluctuations. Specifically, transport coefficients extracted from retarded Green's functions increase throughout the regime $C T \ll 1$. For operators with Schwarzian scaling dimension $Δ>1$, this enhancement is preceded by a universal minimum at a characteristic temperature $T_{\rm min} \propto C^{-1}$, leading to a non-monotonic temperature dependence strikingly similar to that observed in many correlated materials. In contrast, for the case $Δ=1$, relevant for the electrical conductivity, the transport coefficient evolves monotonically toward a constant value. Our results identify universal signatures of near-horizon quantum gravity in the transport properties of holographic quantum matter.

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arXiv2026

Quantum-Corrected Evaporation and Absorption Cross-Section of Near-Extremal Rotating Black Holes

We revisit the Hawking evaporation history of low-temperature rotating black holes by taking into consideration the strong quantum fluctuations known to be present in the near-horizon, near-$\mathrm{AdS_2}$ throat region governed by an effective action that includes Schwarzian and two gauge modes. Imposing compatibility of this quantum framework with the semiclassical results creates a novel link of the black hole angular momentum and electric charge before and after emission, leading to a nontrivial interplay among the superradiance effect, eigenstate thermalization hypothesis and microscopic statistic description. We evaluate single scalar (neutral and charged) emission of Kerr-Newman and single and di-particle emission of photons, gravitons and spinors in the Kerr spacetime. We uncover that quantum corrections may affect late time evaporation rates, which further slows down the whole evaporation process because of the near-balance between the $s$-wave channel and the superradiance channel. Specifically, we find energy decay of the form $E(t)\sim t^{-8/21}$ for neutral scalar emission of a small, slowly rotating and charged black hole which differs from the analogous spherically symmetric quantum correction $E(t)\sim t^{-2/5}$ already suppressed with respect to the semiclassical rate $E(t)\sim t^{-1}$. We also discuss the quantum cross section for rotating black holes and point out various new features.

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arXiv2026

Explorations of Universality in the Entropy and Hawking Radiation of Non-Extremal Kerr AdS$_4$ Black Holes

We comprehensively discuss various microscopic approaches to the Bekenstein-Hawking entropy for rotating, electrically charged, asymptotically AdS$_4$ non-extremal black holes in gauged supergravity. We apply the covariant phase space formalism to the near-horizon region to obtain a Cardy-formula-based microscopic explanation for the entropy, consistent with the Kerr/CFT correspondence. From the dual boundary CFT point of view, we estimate the free partition function in the matrix model approximation in the high-temperature regime and find qualitative agreement with the supergravity answer. All these different approaches match in the appropriate limits and support the universality of AdS black hole entropy even at high temperatures, far away from extremality. Prompted by the consistency of the results of statistical explanations for the AdS$_4$ black hole entropy, we discuss aspects of the rate of Hawking radiation at high temperatures from the CFT$_2$ perspective and found it to be universally proportional to the horizon area.

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arXiv2026

Quantum-Corrected Hawking Radiation from Near-Extremal Kerr-Newman Black Holes

Near-extremal black holes have a long AdS$_2$ throat in their near-horizon region. Quantum fluctuations in the throat region are effectively governed by a quantum version of Jackiw-Teitelboim gravity with matter and are strongly coupled at low temperatures. We investigate how these quantum fluctuations affect the spectrum of emission of particles during Hawking radiation. We systematically consider the cases of Kerr and Kerr-Newman black holes for emission of scalar particles and discuss photon and graviton emission from the Kerr background. We find that at very low temperatures the quantum fluctuations radically change the nature of particle emission. Unlike the generic suppression of particle emission in the spherically symmetric Reissner-Nordström case, we uncover that for particles with non-vanishing angular momentum, the quantum-corrected emission can be substantially enhanced with respect to the standard semiclassical result.

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arXiv2026

A Universality Theorem for the Quantum Thermodynamics of Near-Extremal Black Holes

We prove that the one-loop contribution from tensor modes to the thermodynamic entropy of near-extremal black holes is universal. Our proof applies to asymptotically flat, Anti-de-Sitter and de-Sitter black holes; it also covers spherical, axial and planar symmetries. We consider black hole configurations with and without matter sectors and explicitly discuss Abelian gauge fields and neutral scalar fields with arbitrary potential. We demonstrate that under certain conditions, the thermodynamics of near-extremal black holes contains a one-loop contribution from the tensor modes that equals $\frac{3}{2}\log (T_{\rm Hawking}/T_q)$. The proof of this theorem also shows explicitly how the Schwarzian modes appear universally in near-extremal geometries in dimensions four, five and six. We apply this theorem to Kerr-de-Sitter black holes as an explicit example.

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arXiv2025

Quantum Corrections in the Low-Temperature Fluid/Gravity Correspondence

Attempts to construct a low-temperature version of the fluid/gravity correspondence have faced obstacles manifested in the form of logarithmic terms in the frequency, $\log(ω)$, leading to non-local in time constitutive relations for the stress tensor and the charge current. These difficulties can be broadly presented as a breakdown of the hydrodynamic description due to additional infrared modes. We employ new quantum insights into the physics of near-extremal black holes, brought about in the context of Jackiw-Teitelboim gravity, as an effective description of quantum fluctuations in the throat, to revisit the fluid/gravity correspondence at very low temperatures. The quantum corrections naturally include a new length scale, $C$, and an effective action that parametrizes the breaking of near-horizon symmetries. We show that with an appropriate choice of order of limits in the derivative expansion within the low-temperature regime, the $\log(ω)$ infrared divergence can be resolved. By quantum averaging the infrared Schwarzian modes as an effective extra contribution to the long-wavelength fluid modes, the resulting low-temperature effective fluid description is consistent. We present the dispersion relations for all the relevant hydrodynamic modes. We also revisit the shear viscosity to entropy density ratio and find that at very low temperatures the universal $\frac{1}{4π}$ bound is violated due to quantum correction.

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arXiv2025

Quantized Giant Gravitons as the Periodic Table of Supersymmetric States: D3, M2 and M5

We consider giant gravitons in the probe approximation when they are described by classical brane configurations in AdS$_{p+2}\times S^{q+2}$ wrapping a particular $q$-cycle and spinning in $S^{q+2}$. We quantize the full set of fluctuations of these configurations and show that they are sufficient to capture all the supersymmetric single-letter partition functions of the dual field theory. We explicitly discuss the cases of D3, M2 and M5 branes and reproduce the single-letter indices for all fractions of supersymmetry. We also provide a new derivation of the full finite-$N$ half-BPS index by promoting certain fluctuations to matrix-valued fields. We elaborate on the obstructions for the general finite-$N$ computations. Given that the single-letter partition functions are the building blocks of all supersymmetric enumerations, including for the black hole entropy, our work provides a direct gravitational counting of those degrees of freedom modulo finite-$N$ obstacles due to non-Abelian effects.

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arXiv2025

Universal Cardy-Like Behavior of 3D Partition Functions from Supersymmetric Localization

We investigate 3d $\mathscr{N}=2$ supersymmetric gauge theories on $S^1 \times S^2$ and the corresponding 2d effective field theories arising in the limit of small ratio of radii, $β=R_{S^1}/R_{S^2}\to 0$. We evaluate the exact partition function of these theories in the framework of supersymmetric localization on curved backgrounds. As a result, we establish a finite-$N$ map between a particular, superconformal-index-inspired partition function and the topologically twisted index. Taking the large-$N$ limit of the partition functions, we reproduce the entropy functions of either spherically symmetric, magnetically charged, or rotating, electrically charged asymptotically AdS$_4$ black holes. We then recast the problem of evaluating the 3d partition functions directly in the framework of rigid supersymmetry. By carefully tracking the background fields, we find that in the small-$β$ limit, the partition functions of these 3d large-$N$ superconformal field theories have a universal behavior related to the coefficients of the R-symmetry or flavor symmetry 2-point current correlation functions, thus obtaining a universal Cardy-like formula for 3d $\mathscr{N}=2$ superconformal field theories.

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arXiv2025

Krylov Complexity in Mixed Phase Space

We investigate the Krylov complexity of thermofield double states in systems with mixed phase space, uncovering a direct correlation with the Brody distribution, which interpolates between Poisson and Wigner statistics. Our analysis spans two-dimensional random matrix models featuring (I) GOE-Poisson and (II) GUE-Poisson transitions and extends to higher-dimensional cases, including a stringy matrix model (GOE-Poisson) and the mass-deformed SYK model (GUE-Poisson). Krylov complexity consistently emerges as a reliable marker of quantum chaos, displaying a characteristic peak in the chaotic regime that gradually diminishes as the Brody parameter approaches zero, signaling a shift toward integrability. These results establish Krylov complexity as a powerful diagnostic of quantum chaos and highlight its interplay with eigenvalue statistics in mixed phase systems.

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arXiv2025

The Superconformal Index and Black Hole Instabilities

The superconformal index of ${\cal N}=4$ supersymmetric Yang-Mills theory with gauge group $\mathrm{U}(N)$ has provided powerful insights into the entropy of supersymmetric black holes in AdS$_5\times S^5$, including some sub-leading logarithmic and non-perturbative corrections. Recently, the phase space of supersymmetric solutions has been argued to contain configurations other than the asymptotically AdS$_5$ black hole. Such configurations include the so-called grey galaxies where the black hole at the center is surrounded by a gas of gravitons. By numerically evaluating the superconformal index of ${\cal N}=4$ supersymmetric Yang-Mills at small values of $N$, we detect systematic deviations from the entropy of black holes with two distinct angular momenta. We find that the giant graviton expansion of the index is a numerically efficient way of evaluating the index that complements the direct character evaluation and allows for explicit access to $N\le 15$ with up to two giant gravitons in the expansion. We find it remarkable that a supersymmetric quantity in field theory, usually thought of as a rigid counting observable, indeed contains information about different phases in the space of supersymmetric solutions on the gravity side.

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arXiv2025

A Four-dimensional Gauge Theory Perspective on Quantum K-theory

The two-dimensional gauged linear sigma model has provided a physical model for the quantum cohomology of a Kähler manifold, $X$. A three-dimensional version of such construction has recently been shown to shed light on models of quantum K-theory of $X$. We consider an $\mathcal{N}=1$ four-dimensional version consisting of a $U(1)$ vector multiplet and chiral multiplets, generalizing the two-dimensional $\mathcal{N}=(2,2)$ setup. We compute the four-dimensional partition function on $D^2\times \mathbb{T}^2$ and demonstrates that it satisfies a difference equation which reduces to the deformed quantum K-theoretic one in the appropriate limit. We also demonstrate, though indirectly, that 4d invariants reduce to 3d quantum K-theory invariants in the same limit.

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arXiv2024

Quantum Corrections to Holographic Strange Metal at Low Temperature

The holographic approach to the strange metal phase relies on near-extremal asymptotically AdS$_4$ electrically charged black branes with important input from their AdS$_2$ near-horizon throat geometry. Motivated by the current understanding of the role of quantum fluctuations in the throat of near-extremal black holes, we revisit some transport properties. We model quantum gravitational and gauge fluctuations in the throat region by adopting results in Jackiw-Teitelboim gravity, effectively leading to quantum corrections for the dual CFT$_1$ Green's function in the near-horizon infrared region. We use the quantum-corrected Green's function to compute the conductivity for (2+1)-dimensional holographic strange metals and obtain corrections for the DC resistivity and the optical conductivity. We also compare the quantum-corrected holographic approach with results from the complex Sachdev-Ye-Kitaev model and point out qualitative differences. Although experimental detection for the quantum-corrected holographic approach to the DC resistivity requires higher precision than current experimental accuracy, future experiments with improved technologies could detect these quantum corrections. Interestingly, including quantum corrections to the optical conductivity does provide a plausible explanation for the experimental anomalous power-law behavior detected in various strange metals.

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arXiv2024

Explicit Entropic Proofs of Irreversibility Theorems for Holographic RG Flows

We revisit the existence of monotonic quantities along renormalization group flows using only the Null Energy Condition and the Ryu-Takayanagi formula for the entanglement entropy of field theories with anti-de Sitter gravity duals. In particular, we consider flows within the same dimension and holographically reprove the $c$-, $F$-, and $a$-theorems in dimensions two, three, and four. We focus on the family of maximally spherical entangling surfaces, define a quasi-constant of motion corresponding to the breaking of conformal invariance, and use a properly defined distance between minimal surfaces to construct a holographic $c$-function that is monotonic along the flow. We then apply our method to the case of flows across dimensions: There, we reprove the monotonicity of flows from $\mathrm{AdS}_{D+1}$ to $\mathrm{AdS}_3$ and prove the novel case of flows from $\mathrm{AdS}_5$ to $\mathrm{AdS}_4$.

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arXiv2024

Binary AdS black holes coupled to a bath in Type IIB

We construct Type IIB string theory setups which, via double holography, realize two gravitational systems in separate AdS spaces which interact with each other and with a non-gravitational bath. We employ top-down string theory solutions with concrete field theory duals in the form of 4d $\mathcal N=4$ SYM BCFTs and a first-principles notion of double holography. The setups are used to realize pairs of `near' and `far' black holes from the perspective of the bath, which exchange Hawking radiation with each other and radiate into the bath. We identify three phases for the entropy in the bath characterized as no island, partial island and full island, and discuss the entropy curves. The setups differ from the black hole binaries observed in gravitational wave experiments but may capture certain aspects.

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arXiv2024

Discontinuity in RG Flows Across Dimensions: Entanglement, Anomaly Coefficients and Geometry

We study the entanglement entropy associated with a holographic RG flow from $\textrm{AdS}_7$ to $\textrm{AdS}_{4} \times \mathbb{H}_3$, where $\mathbb{H}_3$ is a $3$-dimensional hyperbolic manifold with curvature $κ$. The dual six-dimensional RG flow is disconnected from Lorentz-invariant flows. In this context we address various notions of central charges and identify a monotonic candidate $c$-function that captures IR aspects of the flow. The UV behavior of the holographic entanglement entropy and, in particular its universal term, display an interesting dependence on the curvature, $κ$. We then contrast our holographic results with existing field theory computations in six dimensions and find a series of new corrections in curvature to the universal term in the entanglement entropy.

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