Correlators at large c without information loss

TL;DR

This work analyzes four-point correlators with two heavy and two light operators in the D1D5 CFT and its AdS$_3$ gravity dual. It shows that at the free orbifold point these correlators are protected and can be organized by Virasoro and affine blocks, with the large $c$ limit not producing Euclidean spurious singularities due to contributions from affine descendants. On the gravity side, the heavy states map to regular AdS$_3\times S^3\times T^4$ geometries; solving the bulk wave equation yields two-point functions for light operators that exactly match the CFT results, including twisted-sector data. The results hint at a general mechanism in unitary CFTs whereby heavy-light correlators avoid large-$c$ pathologies, offering insights into information encoding in black hole microstates and supporting fuzzball-type pictures.

Abstract

We study a simple class of correlators with two heavy and two light operators both in the D1D5 CFT and in the dual AdS$_3 \times S^3 \times T^4$ description. On the CFT side we focus on the free orbifold point and discuss how these correlators decompose in terms of conformal blocks, showing that they are determined by protected quantities. On the gravity side, the heavy states are described by regular, asymptotically AdS$_3 \times S^3 \times T^4$ solutions and the correlators are obtained by studying the wave equation in these backgrounds. We find that the CFT and the gravity results agree and that, even in the large central charge limit, these correlators do not have (Euclidean) spurious singularities. We suggest that this is indeed a general feature of the heavy-light correlators in unitary CFTs, which can be relevant for understanding how information is encoded in black hole microstates.