Arrival & coffee

Gabriel Wong (University of Oxford)

3d gravity from an ensemble of approximate CFTs

Abstract: One of the major insights gained from holographic duality is the relation between the physics of black holes and quantum chaotic systems. This relation is made precise in the duality between two dimensional JT gravity and random matrix theory.  In this work, we generalize this to a duality between AdS3 gravity and a random ensemble of approximate CFT's.  The latter is described by a combined tensor and matrix model, describing the OPE coefficients and spectrum of a theory that approximately satisfies the bootstrap constraints.   We show that the Feynman diagrams of the random ensemble produce a sum over 3 manifolds that agrees with the partition function of 3d gravity.  A crucial element of this dictionary is the Virasoro TQFT, which defines the bulk gravitational path integral via the cutting and sewing relations of topological field theory. This TQFT has gravitational edge modes degrees of freedom whose entanglement gives rise to gravitational entropy.

Coffee & discussion

Matthew Dodelson (CERN)

Black hole bulk-cone singularities

Abstract: Correlators in field theories at finite temperatures have singularities on the light cone. Are there any other singularities? In this talk, I will address this question in the context of holographic theories in the black hole phase. Two points on the AdS boundary can be connected by a null geodesic in the bulk, leading to a so-called bulk-cone singularity. These new singularities were previously conjectured by analyzing the geodesic approximation, but we will derive them in full generality by developing the technology of thermal Regge theory. The functional form of the singularity leads to sharp signatures of the AdS photon sphere in the boundary CFT, including an identification of the boundary dual of the angular velocity and Lyapunov exponent associated with the photon sphere. I will also comment on the resolution of the singularity by stringy effects.

Reception