Bulk Phase Shift, CFT Regge Limit and Einstein Gravity

Understand

The bulk phase shift, related to a CFT four-point function, describes two-to-two scattering at fixed impact parameter in the dual AdS spacetime.

• We describe its properties for a generic CFT and then focus on large $N$ CFTs with classical bulk duals.
• We compute the bulk phase shift for vector operators using Regge theory.
• We use causality and unitarity to put bounds on the bulk phase shift.