Solitonic Symmetry: Cohomology with TFT Coefficients

We review the formalism of https://arxiv.org/pdf/2307.00939, which develops the theory of solitonic symmetry in quantum field theory. The algebraic structure of solitonic symmetry is determined by the fusion of topological functionals in a given path-integral formulation of topological field theory, and acts generically on topological defects determined by homotopy classes of maps to a “space of fields.” We will argue that the structure of solitonic symmetry in a theory with field space (Y) assembles into what looks like the cohomology of (Y) with coefficients in TFTs. We study this formalism in examples and show in particular that the maximal invertible solitonic subsymmetry reduces to the expected result.