2 papers
math-ph2026
Anomalies, higher symmetries, and homotopy theory I: crossed precosheaves and a nonabelian Cech construction
Anton Kapustin, Shixiong Xu
Symmetries of a quantum field theory or a quantum lattice model are expected to be described not by a group but by a homotopy type, whose homotopy groups are the higher symmetry gr…
math-ph2025
Higher symmetries and anomalies in quantum lattice systems
Anton Kapustin, Shixiong Xu
We define an 't Hooft anomaly index for a group acting on a 2d quantum lattice system by finite-depth circuits. It takes values in the degree-4 cohomology of the group and is an ob…