arXiv subjects

Alessia Segati

Publications and source records attributed to Alessia Segati.

10 recordsLinked to original sources

arXiv2026

Holographic reconstruction for defect CFTs from $\mathrm{AdS}_p \times S^q$ spacetimes

We study defects in superconformal field theories using holography, focusing on the precise derivation of the defect observables from supergravity. We consider $\mathrm{AdS}_p \times S^q$ spacetimes fibered over an interval and coupled to higher-form gauge fields as well as scalar fields. We determine the coordinate system in which the defect geometry admits an asymptotically flat boundary and, in this setup, we systematically apply holographic renormalization to compute the fundamental observables of the defect theory. In particular, we derive the one-point correlators of the bulk fields, the holographic stress tensor, and its Ward identities. We implement explicitly this procedure for line and surface defects in five- and six-dimensional Romans supergravity. The relevant geometries are $\mathrm{AdS}_2\times S^2$, $\mathrm{AdS}_2\times S^3$ and $\mathrm{AdS}_3\times S^2$ backgrounds warped over an interval, preserving four supercharges and asymptotically $\mathrm{AdS}_5$ and $\mathrm{AdS}_6$. In each case, we discuss the implications of our results and compare them with the standard literature on defects in conformal field theory.

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arXiv2025

Defects in 4d SCFTs from supergravity and holographic renormalization

Type IIB string theory admits Janus solutions connecting $\text{AdS}_5$ vacua. These geometries correspond to interface conformal field theories and are naturally described in five-dimensional supergravity as $\text{AdS}_4$ foliations over an interval. In this work, we introduce a novel type of Janus solution in $\text{AdS}_5$, featuring $\text{AdS}_2 \times S^2$ foliations instead of $\text{AdS}_4$. We interpret these solutions as the supergravity duals of line defects in four-dimensional SCFTs and we discuss their D-brane engineering. Our primary tool is Romans supergravity in five dimensions, which provides a simple Type IIB truncation over $S^5$. Within this framework, under specific conditions, we construct regular solutions interpolating between $\text{AdS}_5$ and $\text{AdS}_2 \times \mathbb{R}^3$. These geometries represent one-parameter deformations of $\text{AdS}_5$ vacua and are characterized by a running profile for two-form gauge potentials and a scalar field in the supergravity bulk. Finally, using holographic renormalization, we explicitly compute the on-shell action of the defect and we discuss the one-point functions in the holographic field theory.

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arXiv2023

BBBW on the spindle

We study the spindle compactification of families of AdS$_5$ consistent truncations corresponding to M5 branes wrapped on complex curves in Calabi-Yau three-folds. From the AdS/CFT correspondence these models are dual to $\mathcal{N}=1$ SCFTs obtained by gluing of $T_N$ blocks. The truncations considered here have both vector and hyper multiplets and the analysis of the BPS equations on the spindle allows to extract the central charges. Such analysis gives also consistency conditions for the existence of the solutions. The solutions are then found both analytically and numerically for opportune choices of the charges for some sub-families of truncations. We then compare our results with the one expected from the field theory side, by integrating the anomaly polynomial.

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arXiv2023

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, $\beta=R_{S^1}/R_{S^2}\to 0$. 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-$\beta$ 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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arXiv2023

$T^{1,1}$ truncation on the spindle

We study the compactification of the $\mathcal{N}=2$ AdS$_5$ consistent truncation of the conifold, in presence of a Betti vector multiplet, on the spindle. We derive the BPS equations and solve them at the poles, computing the central charge for both the twist and the anti-twist class, turning on the magnetic charge associated to the baryonic symmetry. Then, in the anti-twist class, where there are choices of the quantized flux that give origin to a positive central charge, we numerically solve the BPS equations interpolating between the poles of the spindle. We conclude by comparing our results with the one obtained from the analysis of the dual field theory, finding an exact agreement.

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arXiv2022

Kerr-Newman black holes from $\mathcal{N}=1^*$

The microstate counting of charged rotating AdS$_5$ supersymmetric black holes has been reformulated in terms of an extremization problem, obtained from the superconformal index of the 4d dual SCFT. On the gravitational side this problem corresponds to the attractor mechanism of the theory KK reduced on AdS$_4$. Such procedure has indeed been successfully applied to some consistent truncations with a known field theory dual description. In this paper we study the case of the Leigh-Strassler fixed point along these lines, finding an agreement between the field theory and the gravitational results.

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arXiv2021

Conformal S-dualities from O-planes

We study 4d SCFTs obtained by orientifold projections on necklace quivers with fractional branes. The models obtained by this procedure are $\mathcal{N}=1$ linear quivers with unitary, symplectic and orthogonal gauge groups, bifundamental and tensorial matter. Remarkably, models that are not dual in the unoriented case can have the same central charges and superconformal index after the projection. The reason for this behavior rests upon the ubiquitous presence of adjoint fields with R-charge one. We claim that the presence of such fields is at the origin of the notion of inherited S-duality on the models' conformal manifold.

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arXiv2021

Expanding on the Cardy-like limit of the superconformal index of 4d $\mathcal{N}=1$ ABCD SCFTs

We study the Cardy-like limit of the superconformal index of generic $\mathcal{N}=1$ SCFTs with ABCD gauge algebra, providing strong evidence for a universal formula that captures the behavior of the index at finite order in the rank and in the fugacities associated to angular momenta. The formula extends previous results valid at lowest order, and generalizes them to generic SCFTs. We corroborate the validity of our proposal by studying several examples, beyond the well-understood toric class. We compute the index also for models without a weakly-coupled gravity dual, whose gravitational anomaly is not of order one.

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arXiv2020

The superconformal index of $\mathcal{N}=4$ $USp(2N_c)$ and $SO(N_c)$ SYM as a matrix integral

We study the superconformal index of 4d $\mathcal{N}=4$ $USp(2N_c)$ and $SO(N_c)$ SYM from a matrix model perspective. We focus on the Cardy-like limit of the index. Both in the symplectic and orthogonal case the index is dominated by a saddle point solution which we identify, reducing the calculation to a matrix integral of a pure Chern-Simons theory on the three-sphere. We further compute the subleading logarithmic corrections, which are of the order of the center of the gauge group. In the $USp(2N_c)$ case we also study other subleading saddles of the matrix integral. Finally we discuss the case of the Leigh-Strassler fixed point with $SU(N_c)$ gauge group, and we compute the entropy of the dual black hole from the Legendre transform of the entropy function.

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arXiv2017

Dephasing assisted transport on a biomimetic ring structure

We address two-level systems arranged in ring configurations affected by static disorder. In particular we investigate the role of dephasing in the transport of an excitation along the ring. We compare the efficiency of the transfer process on isotropic rings and on biomimetic rings modelled according to the structure of light-harvesting complexes. Our analysis provides a simple but clear and interesting example of how an interplay between the coherent dynamics of the system and the incoherent action of the environment can enhance the transfer capabilities of disordered lattices.

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