Hidden Conformal Symmetry in AdS$_2\times$S$^2$ Beyond Tree Level
P. J. Heslop, A. E. Lipstein, M. Santagata
TL;DR
This work reveals a hidden four-dimensional conformal symmetry organizing SU(1,1|2) four-point correlators in AdS$_2\times$S$^2$ beyond tree level. The weight-2 one-loop sector can be recast as a four-dimensional master function arising from a one-loop bubble in AdS$_2\times$S$^2$, obtained by acting with Casimir operators on the tree-level data; the finite part aligns with a four-dimensional uplift described by a weight-3 single-valued polylog combination. Building on this, the authors propose an AdS$_2\times$S$^2$ scalar effective field theory with a derivative interaction whose bulk dynamics should reproduce all-loop four-point correlators in the two-derivative sector, suggesting a non-renormalisable but UV-completable framework that mirrors higher-dimensional organizing principles. The results illuminate how hidden conformal symmetry extends into quantum corrections and offer a tractable toy model for IIB string theory on AdS$_5\times$S$^5$ and the near-horizon physics of extremal black holes, with potential applications to quantum gravity and holographic computations of loop amplitudes.
Abstract
Correlators of a certain one-dimensional superconformal field theory dual to hypermultiplets in AdS$_2\times$S$^2$ exhibit a hidden four-dimensional conformal symmetry which allows one to repackage all tree-level 4-point correlators into a single four-dimensional object corresponding to a contact diagram arising from a massless $φ^4$ theory in AdS$_2\times$S$^2$. This theory serves as a toy model for IIB string theory in AdS$_5\times$S$^5$ and is interesting in its own right because AdS$_2\times$S$^2$ describes the near-horizon limit of extremal black holes in four dimensions. We argue that after acting with an $SU(1,1)\times SU(2)$ Casimir, all one-loop correlators can similarly be encoded by a four-dimensional function which arises from a one-loop scalar bubble diagram in AdS$_2\times$S$^2$, explaining how the hidden conformal symmetry extends beyond tree level. Finally, we conjecture a scalar effective field theory with a derivative interaction in AdS$_2\times$S$^2$ whose Witten diagrams should directly reproduce 4-point correlators to all loops without acting with Casimirs.
