I will present the problem of building local AdS bulk observables from boundary CFT data. Focusing on QFTs coupled to a rigid AdS background, we study the analyticity constraints that bulk locality imposes on bulk-boundary-boundary 3-point functions ("AdS form factors"). We reformulate these constraints as a complete, non-perturbative set of sum rules. These sum rules lead to additional constraints on the boundary CFT on top of crossing, and can be implemented numerically in the bootstrap. We study the flat limit when these "AdS form factors" become form factors. (Based on 2305.07078)

Costello, Witten and Yamazaki proposed a 4d Chern-Simons theory as a unified way to engineer integrable models. In the presence of 'Disorder' defects (for non-ultralocal 2d theories), this correspondence has been established only classically. As a first quantum check, I will derive the matching of 1-loop divergences between the 4d and 2d theories. My assumptions are general and seem to isolate sigma-models among the 2d theories. (Based on 2309.16753)

It is often suggested that integrable 2d sigma models should be renormalizable, however this relationship has only previously been checked in the 1-loop approximation. The aim of this work is to understand what happens beyond 1-loop. We shall pedagogically introduce the lambda- and eta-models, and non-abelian duality. Based on these examples, we confirm that classically integrable sigma models appear to be 2-loop renormalizable if supplemented with a particular choice of finite counterterms, i.e. quantum corrections to the target space geometry. The 2-loop beta-function of the lambda-model is computed, matching the known results for groups and symmetric spaces in the limit when the lambda-model becomes the corresponding non-abelian dual model. This leads to the statement that non-abelian duality commutes with the RG flow beyond 1-loop order. NOTE: Please register to the mailing list at integrability-london.weebly.com to receive the link for the Zoom meeting.