Chern-Weil theory for $\infty$-local systems

Abstract: Let $G$ be a compact connected Lie group. We show that the category $\mathbf{Loc}{\infty}(BG)$ of $\infty$-local systems on the classifying space of $G$, can be described infinitesimally as the category $\mathbf{InfLoc}{\infty}(\mathfrak{g})$ of basic $\mathfrak{g}$-$L_\infty$ spaces. Moreover, we show that, given a principal bundle $\pi \colon P \rightarrow X$ with structure group $G$ and any connection $\theta$ on $P$, there is a DG functor $$\mathcal{CW}{\theta} \colon \mathbf{InfLoc}{\infty}(\mathfrak{g}) \longrightarrow \mathbf{Loc}{\infty}(X), $$ which corresponds to the pullback functor by the classifying map of $P$. The DG functors associated to different connections are related by an $A\infty$-natural isomorphism. This construction provides a categorification of the Chern-Weil homomorphism, which is recovered by applying the functor $\mathcal{CW}_{\theta}$ to the endomorphisms of the constant local system.