Abstracts

Pawel Caputa : Sphere partition functions and cut-off AdS

The talk is will be based on my recent work: We consider sphere partition functions of TT deformed large N conformal field theories in d=2,3,4,5 and 6 dimensions, computed using the flow equation. These are shown to non-perturbatively match with bulk computations of AdSd+1 with a finite radial cut-off. Finally, we show that the sphere partition functions, modulo bulk-counterterm contributions, can be reproduced from Wheeler-DeWitt wave functions.

Frank Ferrari ： New IR Behaviour in Generalized SYK and Melonic Quantum Mechanics

I will start with a brief discussion of some general properties of CFT1, emphasising that they are compatible with a more general IR behaviour than has been considered so far in the literature. I will then introduce a new class of complex SYK models that realise explicitly this new behaviour: the Euclidean two-point function decays as a power law for large Euclidean time \tau, but with two distinct dimensions according to whether \tau goes to plus infinity or minus infinity. The models also have an interesting large q limit, in which the Schwinger-Dyson equations reduce to a set of two coupled non-linear differential equations. The space of solutions of these equations has a very interesting structure; the number of physically acceptable solutions can be very large, even infinite in some limit. Several interesting questions about these new models, including the behaviour of OTOCs and the effective description in terms of a generalized Schwarzian action remain open.

Koji Hashimoto : Deep learning and AdS/CFT

We shall discuss the relation between the holographic principle and the deep learning. To find a gravity dual for a given quantum field theory is an inverse problem, and we apply the machine learning approach to the inverse problem. QCD data such as chiral condensate produces an emergent geometry, with which we can calculate Wilson loop as a prediction.

Akihiro Ishibashi : Black Holes in General Relativity Revisited

Abstract: In the first part, I shall attempt to provide an overview about basic properties of black holes in general relativity, such as the topology, rigidity, and no-hair theorems. Along the way, I shall also give a brief review on topological censorship and wormholes. This part involves mathematical techniques of differential topology developed mainly by Penrose and Hawking. In the second part, I shall discuss some of the fundamental open issues, including the recent progress in the stability problem of stationary black holes in asymptotically flat spacetimes, instability of black holes in asymptotically AdS spacetimes, and the current state of knowledge concerning cosmic censorship conjecture.

Kengo Maeda : Null Energy conditions in holographic theories

Null energy condition (NEC) is the key condition for the proof of the singularity theorem, topological censorship, and other important theorems in classical general relativity. Although it is satisfied for the typical classical matter fields, the local NEC can be violated when one considers quantum field effects. So, as an alternative non-local energy condition, achronal averaged null energy condition (ANEC) or quantum null energy condition (QNEC) has been recently proposed. First, we briefly review the non-local null energy conditions. We next show under what conditions the ANEC or QNEC can be violated in strongly coupled field theories in curved spacetime in the framework of the AdS/CFT duality.

Tatsuma Nishioka : Quantum information measures and quantum field theory

I will review some aspects of quantum information measures in quantum information theory, and discuss their prominent roles as a measure of degrees of freedom (C-function) under renormalization group flows in quantum field theory.

Masaki Shigemori : Black hole microstates

I will review some recent developments in understanding black-hole microstates in string theory. In particular, Iwill discuss the construction of smooth horizonless solutions ofsupergravity that represent some microstates, called superstrata.

Junggi Yoon : Chaos in three-dimensional higher spin gravity

In this talk, I'll discuss SL(N) Chern-Simons higher spin gravity, and its boundary on-shell action. Then, I will discuss gravitationally dressed bi-local objects such as master field in the SL(N) Vasiliev equation and Wilson line. And, I will explain their soft higher spin mode expansion to derive soft mode eigenfunctions. I will also discuss the general form of soft mode eigenfunctions from W-Ward identity and null relation in W_N minimal model. Finally, from the on-shell action and the soft mode eigenfunction, I will evaluate the out-of-time-ordered correlators.

Kentaro Yoshida : Dressed S-matrix and TT-deformation in flat space Jackiw-Teitelboim gravity

I will discuss a quantum gravity effect from the viewpoint of dressed S-matrix and TT-deformation in a simple model, flat space Jackiw-Teitelboim gravity. This talk is mainly based on the work 1706.06604 by S. Dubovsky et al.