Landau diagrams in AdS and S-matrices from conformal correlators

Understand

Quantum field theories in AdS generate conformal correlation functions on the boundary, and in the limit where AdS is nearly flat one should be able to extract an S-matrix from such correlators.

• We discuss a particularly simple position-space procedure to do so.
• It features a direct map from boundary positions to (on-shell) momenta and thereby relates cross ratios to Mandelstam invariants.
• This recipe succeeds in several examples, includes the momentum-conserving delta functions, and can be shown to imply the two proposals in arXiv:1607.06109 based on Mellin space and on the OPE data.