Categorical dualtiy for Yetter-Drinfeld C*-algebras. Beyond the braided-commutative case
Lucas Hataishi, Makoto Yamashita
TL;DR
We address the problem of categorifying Yetter–Drinfeld $G$-C$^*$-algebras via a Tannaka–Krein framework. The main approach constructs a correspondence with centrally pointed cyclic $C^*$-$\mathrm{Rep}(G)$-bimodule categories using a generator and a half-braiding, and provides explicit forward and reverse constructions. The key contributions are (i) the equivalence between $\mathcal{YD}(G)$ and $\mathcal{CB}^c(\mathrm{Rep}(G))$, (ii) an explicit description of how to pass from a YD algebra to a central bimodule category and back, and (iii) a study of the moduli of module functors that preserves this duality. The results unify operator-algebraic and tensor-categorical perspectives on quantum group actions, enabling applications to Drinfeld doubles, monoidal invariance, and geometric representation theory.
Abstract
We develop a tensor categorical duality in the sprit of the Tannaka-Krein duality for the C*-algebras admitting the Yetter-Drinfeld module structure over a compact quantum group. Under this duality, given a reduced compact quantum group G, the Yetter-Drinfeld G-C*-algebras correspond to the bimodule categories over the representation category Rep(G), satisfying a certain centrality condition.
