The connected components of affine Deligne--Lusztig varieties

Abstract: We compute the connected components of arbitrary parahoric level affine Deligne--Lusztig varieties and local Shimura varieties, thus resolving the conjecture raised in \cite{He} in full generality (even for non-quasisplit groups). We achieve this by relating them to the connected components of infinite level moduli spaces of $p$-adic shtukas, where we use v-sheaf-theoretic techniques such as the specialization map of \textit{kimberlites}. Along the way, we give a $p$-adic Hodge-theoretic characterization of HN-irreducibility. As applications, we obtain many results on the geometry of integral models of Shimura varieties at arbitrary parahoric levels. In particular, we deduce new CM lifting results on integral models of Shimura varieties for quasi-split groups at arbitrary connected parahoric levels.