Scattering States in AdS/CFT

TL;DR

This paper demonstrates that multi-trace primary states in large N CFTs can be used to define the flat-space S-Matrix in AdS/CFT, with AdS curvature acting as an IR regulator that vanishes in the flat space limit.

Contribution

It provides a CFT-based framework for understanding scattering amplitudes in the flat-space limit of AdS/CFT, connecting boundary states to bulk scattering.

Findings

Transition matrix elements approach bulk scattering amplitudes.

AdS curvature acts as an IR regulator that disappears in the flat space limit.

Multi-trace primary states behave like 'in' and 'out' scattering states.

Abstract

We show that suitably regulated multi-trace primary states in large N CFTs behave like `in' and `out' scattering states in the flat-space limit of AdS. Their transition matrix elements approach the exact scattering amplitudes for the bulk theory, providing a natural CFT definition of the flat space S-Matrix. We study corrections resulting from the AdS curvature and particle propagation far from the center of AdS, and show that AdS simply provides an IR regulator that disappears in the flat space limit.