Speaker
Description
The one-loop amplitude for four tensor multiplets in six-dimensional (2,0) supergravity coupled to n tensor multiplets exhibits a remarkable ultraviolet cancellation when the number of tensor multiplets is tuned to n=21. This value is precisely realised by the low-energy limit of type IIB string theory compactified on K3. In this talk, I will discuss how the same distinguished value appears when the theory is considered on an AdS_3 x S^3 background, where it admits a well-known CFT holographic dual. In particular, I will show how n=21 naturally emerges from bootstrapping the four-tensor correlator at one loop using crossing symmetry and consistency of the OPE. Finally, I will demonstrate the consistency of the AdS correlator with the corresponding flat-space amplitude via the flat-space limit. The talk is based on recent work in collaboration with Francesco Aprile and Hynek Paul.