Anomaly cascade for fermionic symmetry actions

Let C\mathcal{C} be a super modular tensor category with fermionic symmetry data (Gb,s,ω)(G_b,s,\omega), and let B\mathcal{B} be a unitary modular tensor category that is a minimal modular extension of C\mathcal{C}. Let Ep,qE_\infty^{p,q} denote the layers in total degree 44 of the Atiyah–Hirzebruch spectral sequence for the relevant twisted spin bordism theory. The anomaly cascade. The anomaly of the super modular tensor category has four layers: the first, valued in E0,4E_\infty^{0,4}, is the obstruction to giving the modular extension time-reversal symmetry; the second, valued in E2,2E_\infty^{2,2}, is the obstruction to extending ρ:GbAut(C)\rho:G_b\to\operatorname{Aut}(\mathcal{C}) to ρˇ:GbAut(B)\check\rho:G_b\to\operatorname{Aut}(\mathcal{B}); the third, valued in E3,1E_\infty^{3,1}, is the obstruction to extending the symmetry-fractionalization data ηa(g,h)\eta_a({\bf g},{\bf h}); and the fourth, valued in E4,0E_\infty^{4,0}, is the anomaly of the extended GbG_b-action on B\mathcal{B}. This describes the four obstruction layers governing fermionic symmetry anomalies through a minimal modular extension. The source presents this as an interpretation attributed to Bulmash and Barkeshli and does not state a resolution.

Sources & referencesView supporting material

Primary source

Arun Debray, Weicheng Ye and Matthew Yu, “Bosonization and Anomaly Indicators of (2+1)-D Fermionic Topological Orders”, arXiv:2312.13341 (2025).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.