Meromorphic vector bundles on the Fargues--Fontaine curve
Ian Gleason, Alexander B. Ivanov, Felix Zillinger
TL;DR
The paper constructs and analyzes the stack of meromorphic G-bundles on the Fargues--Fontaine curve, forging a bridge between the schematic Kottwitz stack ${\mathfrak B}(G)$ and the analytic stack ${\rm Bun}_G$ to illuminate the geometric local Langlands program. It introduces ${\rm Bun}_G^{mer}$ and proves two central results: (i) a generic Newton strata identification with Fargues--Scholze charts ${\mathcal M}$, and (ii) a meromorphic comparison theorem extending Fargues' theorem to families, which underpins the full faithfulness of analytification. The work also provides new proofs of a schematic comparison ${\rm Bun}_G^{red}\simeq {\mathfrak B}(G)$ and a topological comparison connecting the topologies of the two stacks. A rich framework of v-stacks, isocrystals, Dieudonné modules, shtukas, and semi-stable filtrations is developed, enabling a precise understanding of Newton strata and their compatibility across meromorphic, analytic, and schematic perspectives. Overall, the results push toward a unified categorical Langlands picture by relating analytic and schematic Langlands categories through a meromorphic intermediary and explicit comparison theorems.
Abstract
We introduce and study the stack of \textit{meromorphic} $G$-bundles on the Fargues--Fontaine curve. This object defines a correspondence between the Kottwitz stack $\mathfrak{B}(G)$ and $\operatorname{Bun}_G$. We expect it to play a crucial role in comparing the schematic and analytic versions of the geometric local Langlands categories. Our first main result is the identification of the generic Newton strata of ${\operatorname{Bun}}_G^{\operatorname{mer}}$ with the Fargues--Scholze charts $\mathcal{M}$. Our second main result is a generalization of Fargues' theorem in families. We call this the \textit{meromorphic comparison theorem}. It plays a key role in proving that the analytification functor is fully faithful. Along the way, we give new proofs to what we call the \textit{topological and schematic comparison theorems}. These say that the topologies of $\operatorname{Bun}_G$ and $\mathfrak{B}(G)$ are reversed and that the two stacks take the same values when evaluated on schemes.
