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A<sc>bstract</sc> We provide a precise relation between an ensemble of Narain conformal field theories (CFTs) with central chargec=n, and a sum of (U(1) × U(1))nChern-Simons theories on different handlebody topologies. We begin by reviewing the general relation of additive codes to Narain CFTs. Then we describe a holographic duality between any given Narain theory and a pure Chern-Simons theory on a handlebody manifold. We proceed to consider an ensemble of Narain theories, defined in terms of an ensemble of codes of lengthnoverℤk × ℤkfor primek. We show that averaging over this ensemble is holographically dual to a level-k(U(1) × U(1))nChern-Simons theory, summed over a finite number of inequivalent classes of handlebody topologies. In the limit of largekthe ensemble approaches the ensemble of all Narain theories, and its bulk dual becomes equivalent to “U(1)-gravity” — the sum of the pertubative part of the Chern-Simons wavefunction over all possible handlebodies — providing a bulk microscopic definition for this theory. Finally, we reformulate the sum over handlebodies in terms of Hecke operators, paving the way for generalizations.
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This content will become publicly available on February 13, 2026
TQFT gravity and ensemble holography
We outline a general derivation of holographic duality between “TQFT gravity” — the path integral of a 3d TQFT summed over different topologies — and an ensemble of boundary 2d CFTs. The key idea is to place the boundary ensemble on a Riemann surface of very high genus, where the duality trivializes. The duality relation at finite genus is then obtained by genus reduction. Our derivation is generic and does not rely on an explicit form of the bulk or boundary partition functions. It guarantees unitarity and suggests that the bulk sum should include all possible topologies. In the case of Abelian Chern-Simons theory with compact gauge group we argue that the weights of the boundary ensemble are equal, while the bulk sum reduces to a finite sum over equivalence classes of topologies, represented by handlebodies with possible line defects.
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- Award ID(s):
- 2310426
- PAR ID:
- 10608105
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2025
- Issue:
- 2
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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