AdS₃ × S³ tree-level correlators: hidden six-dimensional conformal symmetry

We revisit the calculation of holographic correlators in AdS₃. We develop new methods to evaluate exchange Witten diagrams, resolving some technical difficulties that prevent a straightforward application of the methods used in higher dimensions. We perform detailed calculations in the AdS₃× S³× K 3 background. We find strong evidence that four-point tree-level correlators of KK modes of the tensor multiplets enjoy a hidden 6d conformal symmetry. The correlators can all be packaged into a single generating function, related to the 6d flat space superamplitude. This generalizes an analogous structure found in AdS₅× S⁵ supergravity.