We will discuss generalized circular Wilson loops and 1d CFT defined by correlators of operators inserted along the loop following arXiv:1706.00756 and some more recent work.

TRIANGULAR SEMINAR: We propose an integrability setup for the computation of correlation functions of gauge-invariant operators at any value of the 't Hooft coupling and at any order in the large Nc 't Hooft expansion in N = 4 SYM theory. In this multi-step proposal, one polygonizes the string worldsheet in all possible ways, hexagonalizes all resulting polygons, and sprinkles mirror particles over all hexagon junctions to obtain the full correlator. We test our integrability-based conjecture against a non-planar four-point correlator of large half-BPS operators at one and two loops.

TRIANGULAR SEMINAR: New techniques of large N and large D allow to study analytically planar matrix quantum mechanics at strong coupling in a reliable way. Using these techniques, we found a remarkable phase transition in these systems, which is very naturally interpreted as a quantum version of the phenomenon of black hole formation in a gravitational collapse.
Based on 1701.01171, 1707.03431, 1709.07366, 1710.07263 and work in progress.

Non-abelian gauge theories underlie particle physics, including collision processes at particle accelerators. Recently, quantum scattering probabilities in gauge theories have been shown to be closely related to their counterparts in gravity theories, by the so-called double copy. This suggests a deep relationship between two very different areas of physics, and may lead to new insights into quantum gravity, as well as novel computational methods. This talk will review the double copy for amplitudes, before discussing how it may be extended to describe exact classical solutions such as black holes. Finally, I will discuss hints that the double copy may extend beyond perturbation theory.

Discussion of "A spacetime derivation of the Lorentzian OPE inversion formula” by Simmons-Duffin, Stanford and Witten. [1711.03816]

In this talk I will present recent results on the Bethe/Gauge correspondence obtained together with Mathew Bullimore and Hee-Cheol Kim. I will describe new ingredients of the Bethe/Gauge dictionary between the XXX Heisenberg spin chain and 2d N = (2,2) supersymmetric gauge theories. In particular, I will show how to construct off-shell Bethe states as orbifold defects in the A-twisted supersymmetric gauge theory and study their correlation functions. It will allow us to include aspects of algebraic Bethe ansatz in the correspondence. In particular, I will show how to interpret spin chain R-matrices as correlation functions of Janus interfaces for mass parameters.

Discuss 1710.09580

The Information Paradox represents a strong consistency challenge for any quantum theory of gravity. The study of black hole internal structure in String Theory offers the potential to resolve this paradox. I will give an overview of recent work on constructing families of smooth horizonless supergravity solutions describing black hole microstates. Where applicable, I will present a holographic description of these solutions. I will also discuss the physics of an observer falling into a black hole.

Supersymmetric localization is a powerful technique to evaluate a class of functional integrals in supersymmetric field theories. It reduces the functional integral over field space to ordinary integrals over the space of solutions of the off-shell BPS equations. The application of this technique to supergravity suffers from some problems, both conceptual and practical. I will discuss one of the main conceptual problems, namely how to construct the fermionic symmetry with which to localize. I will show how a deformation of the BRST technique allows us to do this. I will then sketch a computation of the one-loop determinant of the super-graviton that enters the localization formula for BPS black hole entropy.

Review of 1710.03934v1

We will discuss "From 3d duality to 2d duality" https://arxiv.org/abs/1710.00926 by Aharony, Razamat and Willett.

Any four dimensional N=2 superconformal field theory (SCFT) contains a subsector of local operator which is isomorphic to a two dimensional chiral algebra. If the 4d theory possesses N=3 or N= 4 superconformal symmetry, the corresponding chiral algebra is an extension the N=2 or (small) N=4 super-Virasoro algebra respectively. In this talk I will present some results on the classification of N=4 chiral algebras and discuss if they can correspond to a 4d theory.

I will discuss integrability in the context of planar AdS4/CFT3, where the CFT is the so-called ABJ model depending on two t'Hooft couplings. When the two couplings are equal, this reduces to the ABJM theory, whose integrable structure is well understood but depends on an unspecified interpolating function of the coupling. I will motivate a proposal that the most general ABJ case is also integrable, and that the two coupling constants l1 and l2 recombine into a single interpolating function h( l1 , l2 ) , so that the spectrum is a function of h only. Extending and idea by N. Gromov and G. Sizov on the ABJM case, an explicit conjecture for the form of h(l1, l2) wil be made, based on the comparison between integrability and localization results. The talk is based on the paper hep-th/1605.04888 with N. Gromov and F. Levkovich-Maslyuk.

I will start by sketching the computation of the topologically twisted index on H2xS1 and its evaluation in ABJM theory in the large N limit with k=1. Then after, I will review the key points behind the construction of magnetically charged (hyperbolic) AdS4 black holes on STU gauged SUGRA and will conclude by stating how the aformentioned index -- upon extremization -- coincides with the entropy of the latter black holes in the large N limit (with k=1).

The goal of this talk is twofold. Firstly, I would like to popularize the segmented string approach for solving the classical string dynamics on certain symmetric spacetimes where the string motion is integrable. This allows for an exact discretization which renders the equation of motion discrete in both space and time. The corresponding string solution is a segmented string. I will review the properties of segmented strings and relate them to discrete-time Toda-type lattices. The second goal of the talk is to understand a concrete setup: a (segmented) string hanging from the boundary of three-dimensional AdS spacetime. According to the gauge/gravity duality, the string in the bulk is dual to a flux tube between a quark-antiquark pair in the boundary field theory. We assume that the string is initially (quasi-)static. Perturbing one of the endpoints creates a large propagating wave on the string. The non-linear time-evolution produces a number of interesting phenomena: energy cascades, pair-creation of cusps, and evaporating regions on the string. If time permits, I will also talk about the string worldsheet as a simple model for gravity, chaos, out-of-time-order four-point functions, and segmented membranes.

Given some chiral conformal field theory (also known as a vertex operator algebra in the mathematics literature), a natural but highly non-trivial task is to classify its representation theory. In this talk, I will use some well known examples of conformal field theories, such as the Virasoro minimal models, to show how certain hard questions in representation theory can be neatly rephrased as comparatively easy questions in the theory of symmetric polynomials. After a brief overview of the theory of symmetric polynomials, I will show how they can be used to classify irreducible representations.

I present an extended version of Riemannian geometry suitable for the description of current formulations of double field theory (DFT). This framework is based on graded manifolds and it yields extended notions of symmetries, dynamical data and constraints. In special cases, we recover general relativity with and without 1-, 2- and 3-form gauge potentials as well as DFT. We believe that our extended Riemannian geometry helps to clarify the role of various constructions in DFT. For example, it leads to a covariant form of the strong section condition. Furthermore, it should provide a useful step towards global and coordinate invariant descriptions of T- and U-duality invariant field theories.

I will give a pedagogical review of how the pure spinor formalism was used to obtain all tree-level amplitudes of the superstring, including all their alpha' corrections.

I will present a light introduction to resurgence, with applications in large N gauge theory and in string theory.