Categorical spin-networks: state-sum invariants of 4-manifolds from higher-gauge theory

arXiv:2609.31365 · math-ph, cond-mat.str-el, hep-th, math.MP, math.QA · Submitted 2026-09-25 · Read on arXiv

math-ph, cond-mat.str-el, hep-th, math.MP, math.QA

Submitted: 2026-09-25

Updated: 2026-09-25

Comments: 53 pages; 24 figures

License: http://creativecommons.org/licenses/by/4.0/

The gist: In this work, we define (3+1) -dimensional topological quantum field theories (TQFTs) and their lattice realizations with input data given by a pivotal fusion 2-category; more precisely, our

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Abstract

In this work, we define (3+1) -dimensional topological quantum field theories (TQFTs) and their lattice realizations with input data given by a pivotal fusion 2-category; more precisely, our framework applies in wider generality to presemisimple locally fusion pivotal tensor 2-categories, which are equipped with a so-called shadow trace. We introduce a decoration of triangulated manifolds by the input data, and develop a 20j-symbol formalism for computing 4-simplex scattering amplitudes. We verify the topological invariance of 20 j-symbol summations under the 4-dimensional Pachner moves. Furthermore, we also construct explicitly a 3-dimensional Levin-Wen-type lattice Hamiltonian model realizing the state-sum invariant. Our construction can be understood as a higher-dimensional analogue of the spin-networks construction for the Turaev-Viro invariant. Examples arising from 2-groups are discussed from the perspective of higher gauge theory.

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