Extended TQFT arising from enriched multi-fusion categories
Hao Zheng
TL;DR
The paper develops an enriched multi-fusion framework to extend the Reshetikhin–Turaev TQFT to dimension zero by encoding modular tensor categories as centers of enriched multi-fusion categories. It constructs a symmetric monoidal (4,3)-category of enriched IUMFCs, showing that every object yields a fully extended 3D TQFT $\mathcal{Z}_{\mathfrak{C}}$, with duals at all levels. The 1-2-3D content of $\mathcal{Z}_{\mathfrak{C}}$ combines the RT TQFT $\mathcal{Z}^{RT}_{\mathcal{C}}$ and the 4D Crane–Yetter framework $\mathcal{A}_{\mathcal{C}}$, while the double theory recovers the Turaev–Viro theory $\mathcal{Z}^{TV}_{\mathcal{C}}$, aligning zero- and higher-dimensional invariants. The work provides evidence for an $SO(3)$-fixed point structure for all objects in the enriched setting and links to gapped/gapless edge descriptions, suggesting broad physical relevance for topological phases and Chern–Simons-type theories.
Abstract
We define a symmetric monoidal (4,3)-category with duals whose objects are certain enriched multi-fusion categories. For every modular tensor category $\mathcal{C}$, there is a self enriched multi-fusion category $\mathfrak{C}$ giving rise to an object of this symmetric monoidal (4,3)-category. We conjecture that the extended 3D TQFT given by the fully dualizable object $\mathfrak{C}$ extends the 1-2-3-dimensional Reshetikhin-Turaev TQFT associated to the modular tensor category $\mathcal{C}$ down to dimension zero.
