Programme

Abstract: We will review recent work on two and maybe three topics. The first concerns spatially dependent and supersymmetric mass deformations, focusing on deformations of N=4 SYM theory that depend on one spatial dimension and preserve conformal invariance of a defect interface. The second concerns a novel class of holographic solutions that describe branes wrapping spindles. Topologically these are two-spheres but they have orbifold singularities (defects) at the two poles. For the final topic, time allowing, we will discuss a few results concerning a programme of understanding GK geometry associated with both supersymmetric AdS2 solutions of M-theory, which can arise as the near horizon limit of AdS4 black holes, and supersymmetric AdS2 solutions of type IIB, which can arise as the near horizon limit of AdS5 black strings.

Abstract: I will sketch some of the inter-relationships between work on boundary critical phenomena in the 1970s and 80s, AdS/CFT in the oughts, and the modern conformal bootstrap program and anomalies today.

Abstract: In this talk, I examine the massless 't Hooft equation. This integral equation governs meson bound state wavefunctions in 2D SU(N) gauge theory in the large-N limit, and it can also be obtained by quantizing a folded string in flat space. The folded string is a limiting case of a more general setup: a four-segmented string moving in three-dimensional anti-de Sitter (AdS) space. I compute its classical spectral curve using celestial variables and planar bipartite graphs, also known as on-shell diagrams or brane tilings. In this more general setup, the 't Hooft equation acquires an extra term, which has previously been proposed as an effective confining potential in QCD. After an integral transform, the equation can be inverted in terms of a finite difference equation. I show that this difference equation has a natural interpretation as the quantized (non-analytic) spectral curve of the string. The spectrum interpolates between equally spaced energy levels in the tensionless limit and 't Hooft's nearly linear Regge trajectory at infinite AdS radius.

Abstract: I will describe a new approach for approximately solving the crossing equations in a general CFT, using stochastic optimisation methods. The main tool will be a Reinforcement Learning algorithm. I will then present concrete applications of this approach in the context of the 6D (2,0) theory and the 1D defect CFT.

Abstract: I will explore a proposal for 3d quantum gravity based on the universality of 2d holographic CFTs at high temperature and reducing to JT gravity in its near-extremal regime. Given such Hilbert space, I will attempt to interpret the black hole entropy as entanglement entropy by extending some ideas in BF theory to non-compact gauge groups (JT gravity) and quantum group deformations (3d gravity).

Abstract: I will attempt to review what is known about AdS vacua in string theory for which the KK scale is parametrically smaller than the AdS scale. I will explain the worries, the Swampland conjectures and some of the dual CFT properties.

Abstract: Classical gravity coupled to a CFT4 (matter) is considered. The effect of the quantum dynamics of matter on gravity is studied around maximally symmetric spaces (flat, de Sitter and Anti de Sitter). The structure of the graviton propagator is modified and non-trivial poles appear due to matter quantum effects. The position and residues of such poles are mapped as a function of the relevant parameters, the central charge of the CFT4, the two R2 couplings of gravity as well as the curvature of the background space-time. The instabilities induced are determined. Such instabilities can be important in cosmology as they trigger the departure from de Sitter space and in some regions of parameters are more important than the well-known scalar instabilities. It is also determined when the presence of such instabilities is unreliable if the associated scales are larger than the ``species" cutoff of the gravitational theory.

Abstract: We investigate the formation of composite states of the goldstino in theories with non-linearly realized supersymmetry and show that the Volkov-Akulov model has an instability towards goldstino condensation. We discuss the limitations and implications of our findings for string models involving anti-brane uplifts.

Abstract: TBA

Abstract: TBA