The entropy of giant gravitons at large charges
There is strong evidence suggesting a one-to-one correspondence between 1/16 BPS states in U(N) N=4 SYM on S3 and states of Giant graviton D3-branes in AdS5xS5, which extend over three independent contractible S3-cycles in the S5. This correspondence has been verified at small enough charges for small N (N<=3) and for large N (at charges ~N or smaller). The question then arises as to whether this correspondence persists for states with large charges.
In this talk, I will show how this correspondence persists at large charges, regardless of the value of N. In particular, this result completes a recent observation and confirms that the entropy of 1/16 BPS black holes in Type IIB SUGRA in AdS5XS5, with charges of order ~N^2>>1, can be understood as coming from a condensate of giant-gravitons in AdS5XS5.
18 April 2023, 14:00
In this talk I will discuss recent developments in the study of 2- and 3-point functions of chiral single-trace scalar operators in four-dimensional N=2 quiver gauge theories. Using supersymmetric localization, it is possible to map the computation of these correlators to an interacting matrix model and obtain expressions that are valid for any value of the ’t Hooft coupling in the planar limit of the theory. In particular, I will focus on the strong-coupling regime, where these expressions allow us to compute the leading and subleading orders of the 3-point functions and of the corresponding structure constants in an analytic way.
12 April 2023, 14:00
2d Integrable Field Theories from 4d Chern-Simons
In recent years various unifying frameworks for understanding 2d integrable field theories have emerged. In this talk I will review the approach based on 4d Chern-Simons theory, due to Costello and Yamazaki, and describe recent progress towards extracting general 2d integrable fields theories from 4d Chern-Simons theory
04 April 2023, 14:30
Branes and symmetries for N=3 SCFTs
I will explain how to derive various results about the generalised symmetry
structure of N=3 and N=4 S-fold SCFTs using holography. The new results in
the N=3 case include the spectrum of 1-form symmetries, their 't Hooft
anomalies, and the existence of non-invertible symmetries for appropriate
choices of global form.
28 March 2023, 14:30
Building string field theory using machine learning
String field theory is a second-quantized formulation of string theory.
While its general properties are well understood, its action is
non-polynomial and requires the determination of complicated subspaces of
the moduli spaces of Riemann surfaces (vertex regions) and some specific
conformal maps. An elegant parametrization is provided by minimal area
metrics built from Strebel differentials on n-punctured spheres, but it
requires solving the notoriously difficult accessory parameter problem. In
this talk, I will describe recent works where we construct the necessary
data for the quartic interaction in terms of neural networks. As a
consistency check, we recover the known quartic term in the closed string
tachyon potential. I will also argue that the method generalizes to higher
orders.
arxiv: 2211.09129
21 March 2023, 14:30
Analytic bootstrap in critical O(N) line defect models
The analytic bootstrap is a powerful technique that allows one to extract
information about the spectrum and the OPE coefficients in conformal field
theories. In the case of conformal defects, where part of the conformal
symmetry is explicitly broken, one can still apply analytic bootstrap
techniques with some due modifications. In particular, if the CFT data can
be expanded as a formal series in some parameter, one can perturbatively
determine the series coefficients using only general considerations about
the theory and very little additional input. In this talk, we focus on a
specific application of these very general ideas to the case of line defect
theories in d=4-ε where the bulk is the critical O(N) model. For instance,
this leads to the extraction of an infinite amount of new CFT data at once.
The results show the great utility of this method also in cases where it
would be possible but inefficient to perform standard diagrammatic
calculations.
14 March 2023, 14:30
Line and Defects in ABJM theories
We revisit the construction of the one-dimensional topological sector of the
N = 6 ABJ(M) theory and study its correlation functions. We argue that these
correlators can be computed exactly through a matrix model. Next, we explore
the supermultiplet of the superconformal field theory living on the line defect
generated by the 1/2 BPS Wilson line. We demonstrate the existence of an
unusual supermultiplet whose super-primary is a constant supermatrix.
We shall also discuss its correlation functions.
07 March 2023, 14:30
The ODE/IM correspondence is a particular link between classical and quantum integrable models. The first instance of the ODE/IM correspondence revealed a surprising connection between works on spectral determinants for specific Sturm-Liouville problems and the functional approach to CFTs. The correspondence holds its roots in the fact that seemingly different quantities in the two contexts fulfil the same set of functional relations with identical analytic and asymptotic properties. On the other hand, the recent discovery that specific irrelevant perturbations of quantum field theories can be studied using integrable models tools and hydrodynamics-type flow equations has triggered a considerable amount of research activity, with applications ranging from models in quantum mechanics to AdS/CFT and nonlinear electrodynamics. The TTbar deformation is probably the most interesting representative of this family of deformations. Our main objective is to unify these two research strands by proving the validity of the ODE/IM after a TTbar perturbation of both the classical and the quantum sides of the correspondence. Our results should be considered a first step toward the study of irrelevant deformations using the ODE/IM correspondence as a powerful quantisation tool.
28 February 2023, 14:30
Disk partition function of open-closed string field theory
Classical solutions of closed string field theory are believed to correspond to consistent backgrounds for closed string propagation. It is therefore of great importance to provide gauge-invariant observables to enable identification of these backgrounds. After a review of closed string field theory, we will construct a new gauge-invariant quantity by coupling the bulk theory to a probe D-brane using a tree-level truncation of quantum open-closed string field theory. When evaluated on a classical solution, the resulting observable will be shown to compute the disk partition function of the new open-closed background.
7 February 2023, 14:30
We present a fully nonlinear, three-dimensional conformal higher-spin gravity model consisting of matter fields coupled to topological gauge fields. The model, which includes colour gauge fields as well as higher-spin gauge fields, provides a non-linear completion of models considered earlier in separate works by Nilsson and Vasiliev. The field equations are formulated using Vasiliev's unfolded formalism and describe the deformation of a noncommutative twistor space geometry with manifest SL(2;R) x O(1,1) symmetry. The resulting classical moduli space provides a factor in a space of boundary states of an AKSZ sigma model serving as a parent for the three-dimensional model as well as its four-dimensional anti-holographic dual, providing a concrete realization of Vasiliev's higher-spin holography proposal of 2012.
2 February 2023, 14:30