Shinji Hirano (Wits), Random geometry approach to TTbar-deformed conformal field theory

In this talk I first review the random geometry approach to the deformation of 2d CFT by the TTbar operator, i.e. the “square” of the stress tensor, which significantly alters the UV behaviour of the theory and might provide a new window into short-distance physics. In the second part, I present the development in this geometric method to compute matter and stress tensor correlators. This part of the discussion includes, in particular, the TTbar-deformation of the conformal anomaly action and the stress tensor OPEs. In the third part, I put forward an alternative or “dual” view on the TTbar-deformed CFT, namely, the equivalence to the undeformed CFT living in an operator/state-dependent TTbar-deformed space. In the last part of this talk, I present our proposal for a gravity dual of the TTbar deformed CFT, translating the random geometry method into the language of AdS/CFT “word by word”, and discuss its relation to the cutoff AdS interpretation.

Francesco Aprile (ICTP-SAIFR), Single Particle operators in N=4 SYM and their correlators

Abstract: Since the advent of the AdS/CFT correspondence it was understood that half-BPS operators are mapped to single-particle states on the gravity side. In this talk I will describe a basis of half-BPS operators in N=4 SYM whose properties reproduce the known properties of single particle states in AdS_5xS^5. The key point is to define single particle operators as those half-BPS operators in N=4 SYM which are orthogonal to all multitrace operators. I will give explicit formulae for this basis and study their correlators in the free theory. Orthogonality is a key property. On the one hand it will imply that large charge single particle operators pop into giant D3 branes, as the AdS graviton does. On the other hand it simplifies dramatically the study of n-point correlators close to maximal extremality. The simplest family of which is indeed exactly vanishing thanks to a multi-point orthogonality theorem which I will prove. Beyond the free theory, correlation functions of single particle operators at strong coupling capture quantum gravity effects in AdS. Time permitting I will flash the latest developments on the subject.

Thiago Fleury (IIP, Natal), AdS₅ × S⁵ supergravity vertex operators

In this talk after a review of the pure spinor formalism, I will explain the construction of the supergravity vertex operators. Previously, the vertex operators were only known close to the boundary of AdS₅ and in a different picture. The vertex operators are states in the cohomology of the BRST operator with ghost number two. The BRST transformations of the worldsheet variables are very complicated in AdS₅ and it is hard to perform manipulations analytically, however one can use numerical methods. In the end of the talk, I will list open problems and explain possible applications such as the computation of string amplitudes.

Changrim Ahn (Ewha), Jordan Blocks in integrable models in Fishnet limit of twisted N=4 SYM theory

In this talk, I will explain how the algebraic Bethe ansatz, main tool in quantum integrable system, fails to explain rich Jordan block structures appearing in some integrable spin chains derived from the fishnet model, a simple cousin of the strongly twisted N=4 SYM theory. I will also explain how the Jordan Block structure can be explained in combinatorics arguments.