arXiv subjects

Vasil Dimitrov

Publications and source records attributed to Vasil Dimitrov.

10 recordsLinked to original sources

arXiv2026

SolutionsX: supergravity theories/solutions as code, with an agentic workflow for machine-verifiable physics

A supergravity solution in the literature is an artifact that cannot be verified without re-deriving it: conventions might not be clearly stated, papers have typos, algebra is tedious. SolutionsX is a Mathematica package that turns an xAct environment, whatever physics it may describe, into a stored, machine-verifiable record: code that replays in a fresh kernel, carries its own verification, and can later be fetched for re-use or extension. The shipped examples are supergravity theories and their solutions, but the scope is anything xAct reaches: abstract tensors, differential forms, spinors in any dimension. We follow one published solution through the entire workflow, benchmark the package's component engine against xAct's, and report on three blind runs of an agentic workflow in which an AI coding agent, given the package and a small toolkit, correctly codified a recent paper in under three hours. A database of such records is useful to researchers today and gives agents worked examples to learn from. The package acts as an internal verifier during the thought process of an agent: a claim is checked in the kernel before it is made.

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arXiv2026

Macroscopic origin of the topologically twisted index on $T^2 \times \Sigma_{\mathfrak{g}}$

We construct a novel family of non-supersymmetric, asymptotically locally AdS$_5$ solutions of five-dimensional minimal gauged supergravity. In Lorentzian signature the solutions describe finite temperature rotating electro-magnetically charged black strings with $S^1\times \Sigma_{\mathfrak{g}}$ horizon topology. In Euclidean signature the solutions are completely smooth and are asymptotic to $T^2\times \Sigma_{\mathfrak{g}}$. We present a detailed analysis of the thermodynamic properties of these gravitational backgrounds, compute their regularized on-shell action and analyze the extremal and supersymmetric limits. The supersymmetric, but non-extremal, limit of the Euclidean backgrounds is a family of complex black saddles and it provides the holographic dual description of the topologically twisted index of 4d $\mathcal{N}=1$ SCFTs placed on $T^2\times \Sigma_{\mathfrak{g}}$. We show that the supergravity regularized on-shell action in this limit is in agreement with the large $N$ limit of the topologically twisted index in the dual SCFT.

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arXiv2026

Projecting Gravitational Fluctuations onto Near-Horizon Throats

We show that, for stationary geometries whose linearized fluctuation equations separate into radial and angular Heun equations, a pair of diffeomorphisms projects the full problem onto two coupled, isospectral Gauss hypergeometric problems in complementary spacetime regions. This projection requires Robin boundary conditions to be imposed at the intersection between the complementary regions, which are uniquely fixed by requiring the two diffeomorphisms to match there. The method provides an independent derivation of recent results obtained from the correspondence between Heun connection coefficients and instanton partition functions in the Nekrasov-Shatashvili limit. As an application, we identify a subset of modes in Kerr-de Sitter and Kerr-anti-de Sitter black holes that, in the near-extremal limit, continuously reduce to a basis of the Schwarzian/Jackiw-Teitelboim functional space of gravitational fluctuations.

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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.

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arXiv2025

AdS$_7$ Black Holes and Holography

We present a detailed study of the regularized on-shell action of the recently found asymptotically AdS$_7$ black hole supergravity solution with three angular momenta and two electric charges. We show that a particular choice of finite counterterms in the holographic renormalization procedure yields a result for the on-shell action of the supersymmetric limit of the black hole solution which is in perfect agreement with the large $N$ limit of the superconformal index of the dual 6d $\mathcal{N}=(2,0)$ $A_{N}$ SCFT on $S^1\times S^5$. We also discuss a generalization of this 7d supergravity background to a new general family of black holes with horizons given by the $L^{p,q,r}$ 5d Sasaki-Einstein manifolds. The regularized on-shell action of these new 7d black holes is also in agreement with supersymmetric localization results for the 6d $\mathcal{N}=(2,0)$ SCFT on $S^1\times L^{p,q,r}$. Finally, we briefly discuss a generalization of known AdS$_5$ gauged supergravity backgrounds to new 5d black holes with $L(p,q)$ lens space horizon topologies.

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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.

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arXiv2022

Wrapped M5-branes and AdS$_5$ Black Holes

We use consistent truncations in supergravity to show that the backreaction of $N$ rotating M5-branes wrapped on a Riemann surface leads to asymptotically AdS$_5$ black hole solutions of 11d supergravity. We discuss the thermodynamic properties of these black holes focusing on their supersymmetric limit. The Bekenstein-Hawking entropy of the supersymmetric black holes scales as $N^3$ and can be reproduced by the superconformal index of the holographically dual 4d $\mathcal{N}=1$ SCFTs of class $\mathcal{S}$.

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arXiv2022

Higher-Derivative Corrections and AdS$_5$ Black Holes

Using recent results in four-derivative 5d $\mathcal{N}=2$ minimal gauged supergravity, we evaluate the regularized on-shell action of the Euclidean solution in this theory that admits a Lorentzian continuation to an AdS$_5$ black hole with one electric charge and two angular momenta. We focus on the supersymmetric limit of this solution and employ holography to show that the result can be expressed purely in terms of angular momentum fugacities and the 't Hooft anomalies for the $\mathrm{U}(1)_{\mathrm R}$ R-symmetry of the dual 4d $\mathcal{N}=1$ SCFT. This holographic calculation is in perfect agreement with recent studies of the 4d $\mathcal{N}=1$ superconformal index ``on the second sheet''. We illustrate the utility of these results in two classes of 4d $\mathcal{N}=1$ holographic SCFTs that have 't Hooft anomalies with suitable large $N$ behavior that leads to non-trivial corrections at first subleading order in the $1/N$ expansion. We also explicitly calculate the Wald entropy of the black hole solution and delineate the leading four-derivative corrections to the Bekenstein-Hawking entropy.

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arXiv2021

Real-Time Holography and Hybrid WKB for BTZ Wormholes

We study probe scalar correlation functions in a Solodukhin wormhole corresponding to the non-rotating BTZ black hole, as a toy model for microstate geometries thereof. Using real-time holography, we obtain the retarded scalar correlator in the wormhole geometry and quantitatively compare it to the result of the hybrid WKB method for the same correlator. We also calculate an off-diagonal correlator $\sim\langle H L L H' \rangle$ involving two different (heavy) wormhole states.

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arXiv2020

Gravitational Waves, Holography, and Black Hole Microstates

Gravitational wave observations of the near-horizon region of black holes lend insight into the quantum nature of gravity. In particular, gravitational wave echoes have been identified as a potential signature of quantum gravity-inspired structure near the horizon. In this paper, we connect such observables to the language of black hole microstates in string theory and holography. To that end, we propose a toy model describing the AdS$_3$ near-horizon region of five-dimensional black holes, inspired by earlier work of Solodukhin. This model captures key features of recently constructed microstate geometries, and allows us to make three observations. First, we relate the language of AdS/CFT, in particular the holographic retarded two-point correlator, to effective parameters modeling the structure that are used in flat space gravitational wave literature. Second, we find that for a typical microstate, the `cap' of the microstructure is exponentially close to the horizon, making it an effective sub-Planckian correction to the black hole geometry, although the microstate geometry itself is classical. Third, using a microcanonical ensemble average over geometries, we find support for the claim that the gravitational wave echo amplitude in a typical quantum microstate of the black hole is exponentially suppressed by the black hole entropy.

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