Past talks 2023
07/12/23
Title: On the giant brane expansion of superconformal indices
Abstract: After reviewing, informally, the giant D3 brane expansion of the superconformal index of 4d N = 4 SYM proposed by Imamura, and Gaiotto and Lee, I will explain how this infinite sum over partition functions counting excitations of D3 branes extending over the internal S^5, is consistent with the counting of microstates dual to AdS_5 BPS black holes, thinking these microstates as excitations of N D3 branes in the conformal boundary of AdS_5. The talk is based on collaborations with Matteo Beccaria, 2305.17730 and 2308.05191.
References: 2305.17730 [hep-th], 2308.05191 [hep-th]
02/11/23
Title: Scale without Conformal Invariance in Dipolar Ferromagnets
Abstract: It is a common belief that isotropic ferromagnets, when tuned to their critical temperature, can be described by an RG fixed point in the universality class of the Heisenberg model. Although this is often a good approximation, ferromagnets always contain dipolar interactions, which lead to a different fixed point called the dipolar fixed point. In this talk, we point out that the dipolar fixed point is a field theory which is scale but not conformal invariant. We show that this dipolar field theory enjoys a shift symmetry, which is responsible for the lack of conformal invariance and explains the non-renormalization of the virial current. In fact, we observe that shift symmetry is the mechanism behind all other currently known models which are scale but not conformal invariant.
References: 2309.02514 [hep-th]
19/10/23
Title: The O(N) monolith reloaded: sum rules and form factor bootstrap
Abstract: In this talk I will discuss the space of two-dimensional quantum field theories with a global O(N) symmetry. Previous works using S-matrix bootstrap revealed a rich space in which integrable theories appear at special points and an abundance of unknown models hinting at a non conventional UV behaviour. In order to gain more information about the unknown models, we extend the S-matrix set-up by including into the bootstrap form factors and spectral functions for operators like stress tensor and symmetry currents. I will explain how this extended set-up works and show how the associated sum rules allow us to put bounds on quantities like the central charge of the underlying conformal theories in the UV. Based on work with M. Correia, A. Georgoudis and A. Vuignier.
References: 2311.03031 [hep-th]
05/10/23
Title: Quantum JT gravity: holography, random matrices and localization
Abstract: In this talk, I will introduce general aspects of two-dimensional classical JT gravity and then perform its exact quantization on the disk topology, exploiting its description in terms of a Schwarzian mode arising on the asymptotic boundary. The correct interpretation of the JT spectral density of states requires the introduction of higher genus saddles to the gravitational path integral and the need to characterize the dual boundary theory as a suitable ensemble of random matrices. JT gravity on the disk also enjoys an equivalent description as a BF gauge theory in the presence of a defect term. In the second part of the talk, I will characterize the methods used in the literature to quantize the theory in this gauge perspective, finally outlining a new approach based on supersymmetric localization.
References: 2307.01274 [hep-th]
21/09/23
Title: Wilson loop correlators at strong coupling in 4d N=2 SCFTs
Abstract: In the first part of the talk we analyse the correlation function between one single-trace scalar operator and a circular Wilson loop in the 4d N = 2 superconformal field theory with gauge group SU(N) and matter transforming in the symmetric and anti-symmetric representations (the so called Type-E theory). By exploiting supersymmetric localization, we resum the perturbative expansion of this correlator in the large-N ’t Hooft limit. Furthermore, using both analytical and numerical techniques, we provide a prediction for the leading term of its strong coupling expansion. While, in the second part of the talk, we consider 4-dimensional N=2 superconformal quiver theories with SU(N)^M gauge group and bi-fundamental matter and we evaluate correlation functions of n coincident Wilson loops in the planar limit of the theory. Exploiting specific untwisted/twisted combinations of these operators and using supersymmetric localization, we are able to resum the whole perturbative expansion and find exact expressions for these correlators that are valid for all values of the ’t Hooft coupling. Moreover, we analytically derive the leading strong coupling behaviour of the correlators, showing that they obey a remarkable simple rule.
References: 2303.08210 [hep-th], 2308.03848 [hep-th]
29/06/23
Title: Holographic perspectives for N=2 SCFTs in the tensionless limit
Abstract: In this talk we discuss the holographic properties of some 4d planar gauge theories in the zero coupling limit, corresponding to the tensionless limit from the string dual perspective. In particular, we consider a special family of theories, arising as orbifolds of N=4 SYM, which realize a circular quiver theory preserving N=2 superconformal invariance. Following the Gaberdiel-Gopakumar derivation, we propose a free field worldsheet theory in the tensionless string limit which is dual to the orbifold gauge theory at the free theory point. In particular, after imposing some specific gauge constraints on the worldsheet degrees of freedom, the spectrally flowed worldsheet spectrum is in one-to-one correspondence with the single trace operators of the 4d theory. Finally, we discuss possible generalizations of this approach,mentioning N=2 SCQCD as the main example.
References: 2206.08795 [hep-th]
08/06/23
Title: Line Operators in Chern-Simons-Matter Theories and Bosonization in Three Dimensions
Abstract: We study Chern-Simons theories at large N with either bosonic or fermionic matter in the fundamental representation. The most fundamental operators in these theories are mesonic line operators, the simplest example being Wilson lines ending on fundamentals. We classify the conformal line operators along an arbitrary smooth path as well as the spectrum of conformal dimensions and transverse spins of their boundary operators at finite 't Hooft coupling. These line operators are shown to satisfy first-order chiral evolution equations, in which a smooth variation of the path is given by a factorized product of two line operators. We argue that this equation, together with the spectrum of boundary operators, are sufficient to determine these operators' expectation values uniquely. We demonstrate this by bootstrapping the two-point function of the displacement operator on a straight line. We show that the line operators in the theory of bosons and the theory of fermions satisfy the same evolution equation and have the same spectrum of boundary operators.
References: 2204.05262 [hep-th], 2212.02518 [hep-th]
18/05/23
Title: Wilson loops for 5d and 3d conformal linear quivers
Abstract: The study of supersymmetric and conformal field theories in diverse dimensions and classification of Type II or M-theory backgrounds with AdS factors as their holographic duals are of substantial interest. In this talk, I focus on the case of conformal and supersymmetric linear quiver field theories in three and five dimensions preserving eight Poincare supercharges. I am mainly interested in Wilson loops as they can be computed exactly in SUSY gauge theories. After a brief description of Hanany-Witten brane setups, using the electrostatic formulation of holographic duals to conformal balanced quivers in five and three dimensions, I will mention the expressions for Wilson loops in antisymmetric representations. In the case of three-dimensional quivers, I present a relation between Wilson loops in an ’electric’ and the ’magnetic/mirror’ descriptions. This talk is based on arXiv:2209.07536.
References: 2209.07536 [hep-th]
04/05/23
Title: ABJM cusp anomalous dimensions from integrability
Abstract: We study the integrability properties of Wilson loops in the N = 6 three-dimensional Chern-Simons-matter (ABJM) theory. We begin with the construction of an open spin chain that describes the anomalous dimensions of operators inserted along the contour of a 1/2 BPS Wilson loop. Moreover, we compute the all-loop reflection matrices that govern the interaction of spin-chain excitations with the boundary, including their dressing factors, and we check them against weak- and strong-coupling results. Furthermore, we propose a Y-system of equations for the cusped Wilson line of ABJM, and we use it to reproduce the one-loop cusp anomalous dimension of ABJM from a leading-order finite-size correction. Finally, we write a set of BTBA equations consistent with the Y-system proposal.
References: 2304.01924 [hep-th]
05/04/23
Title: Matrix Entanglement
Abstract: In gauge/gravity duality, matrix degrees of freedom on the gauge theory side play important role for the emergent geometry. In this paper, we discuss how the entanglement on the gravity side can be described as the entanglement between matrix degrees of freedom in the dual gauge theory. We consider several classes of quantum states to which our approach can be crucial. When applied to fuzzy sphere, matrix entanglement can be used to define the usual spatial entanglement in two-brane or five-brane world-volume theory nonperturbatively in a regularized setup. Another application is to a small black hole in AdS_5 X S^5 that can evaporate without being attached to a heat bath, for which our approach suggests a gauge theory origin of the Page curve. The confined degrees of freedom in the partially-deconfined states play a crucial role in recovery of the Page curve.
References: 2204.06472 [hep-th]
15/03/23
Title: 1/4 BPS AdS3/CFT2
Abstract: With a focus on their CFT interpretation, in this talk I will show you AdS3 solutions in massive type IIA supergravity. From the geometry, we engineer the dual CFT with well-known tools and propose a duality with a precise family of quivers.
References: 2204.04538 [hep-th]
01/03/23
Title: BPS line operators and topological sectors
Abstract: I will present a new supersymmetric configuration with line defects and local operators in 3d theories with N=4 SUSY. In particular, I will consider operators that are part of conserved current multiplets and thus associated with relevant SUSY deformations. Building on these observations, one can write down the generating-functional for correlation functions of superconformal primaries of current multiplets. I will generalize the construction to include line defects and use it to derive exact relations for defect correlation functions of conserved currents. As a concrete application, I will apply this method in the case of the 1/2-BPS Wilson line in ABJM and combine it with localization leading to an alternative formula for the bremsstrahlung.
References: 2301.07035 [hep-th]
15/02/23
Title: Interpolating WLs and enriched RG flows
Abstract: I will explain how to interpolate between different BPS Wilson loops in ABJM theory and how the interpolating parameters renormalize, leading to non-trivial RG flows connecting such BPS operators.
References: 2211.16501 [hep-th]
25/01/23
Title: Black Holes and Statistical Physics
Abstract: I will review classical and recent advances in our understanding of the relation between black holes and statistical physics. The main guiding compass will be the supersymmetric examples that have been recently understood in the context of AdS/CFT.
References: 2301.00763 [hep-th]