Boundary topological orders of (4+1)d fermionic $\mathbb{Z}_{2N}^{\mathrm{F}}$ SPT states
Abstract
We investigate (3+1)d topological orders in fermionic systems with an anomalous symmetry, where its subgroup is the fermion parity. Such an anomalous symmetry arises as the discrete subgroup of the chiral U(1) symmetry of copies of Weyl fermions of the same chirality. Inspired by the crystalline correspondence principle, we deform the anomalous symmetry of (3+1)d Weyl fermion to the anomalous symmetry. Then we microscopically construct symmetry-preserving gapped boundary states of the closely-related (4+1)d symmetry-protected topological (SPT) state (with being the -fold rotation), whenever it is possible. In particular, for , we show that the (3+1)d symmetric gapped state admits a topological gauge theory description at low energy, and propose that a similar theory saturates the corresponding anomaly. For , our construction admits no topological quantum field theory (TQFT) symmetric gapped state; while for , we find a non-TQFT symmetric gapped state via stacking lower-dimensional (2+1)d non-discrete-gauge-theory topological order inhomogeneously. For other values of , no symmetric gapped state is possible within our construction, which is consistent with the no-go theorem by Cordova-Ohmori.
Keywords
Cite
@article{arxiv.2411.05786,
title = {Boundary topological orders of (4+1)d fermionic $\mathbb{Z}_{2N}^{\mathrm{F}}$ SPT states},
author = {Meng Cheng and Juven Wang and Xinping Yang},
journal= {arXiv preprint arXiv:2411.05786},
year = {2026}
}
Comments
16 pages, 3 figures