Triangle Seminars

Abstract:
We will discuss how to bootstrap string theory in AdS, using N=4 SYM as a concrete example. The first lecture will review the basic ingredients of AdS/CFT: the definitions of AdS and CFT, the correspondence between Kaluza–Klein modes and single-trace operators, and the relation between string scattering in AdS and correlation functions of Kaluza–Klein modes in the CFT. The second lecture will focus on the stress-tensor multiplet four-point function, including its conformal block expansion, the constraints imposed by superconformal Ward identities, and its formulation in Mellin space. The third lecture will introduce the flat-space limit, explain how it acts on the conformal block expansion, and discuss the spectrum of single-trace operators that survives at strong coupling. In the final lecture, we will go beyond the flat-space limit and study the first AdS correction. We will introduce a worldsheet ansatz for this correction and show how matching it to the conformal block expansion fixes the correction completely.

Abstract:
We investigate gravitational dynamics in the presence of finite timelike boundaries with conformal boundary conditions. We focus on the limit in which the conformal boundary approaches a black hole or cosmological horizon. In this regime, potentially exponentially growing perturbations are attenuated, and we find a hierarchy of modes localized near the conformal boundary. In particular, we uncover sound and shear modes that admit an interpretation in terms of a conformal fluid with shear-viscosity-to-entropy-density ratio \eta/s=1/(4\pi). For the AdS4 black brane, we track these modes numerically as the boundary is moved from the near-horizon region towards the asymptotic AdS boundary, and find that they continuously connect to the hydrodynamic sound and shear modes of the fluid/gravity correspondence.

Abstract:
TBA

Abstract:
TBD.