Finite group actions on dg categories and Hochschild homology

Abstract

We prove a decomposition of the Hochschild homology groups of the equivariant dg category $\mathscr{C}^G$ associated to a small dg category $\mathscr{C}$ with direct sums on which a finite group $G$ acts. When the ground field is $\mathbb{C}$ this decomposition is related to a categorical action of $\text{Rep}(G)$ on $\mathscr{C}^G$ and the resulting action of the representation ring $R_\mathbb{C}(G)$ on $HH_\bullet(\mathscr{C}^G)$.