A stacky $p$-adic Riemann--Hilbert correspondence on Hitchin-small locus
Yudong Liu, Chenglong Ma, Xiecheng Nie, Xiaoyu Qu, Yupeng Wang
TL;DR
This work develops a stacky $p$-adic Riemann--Hilbert correspondence for Hitchin-small objects on a semi-stable formal scheme over a perfectoid base ${\mathcal O}_C$, through the construction of a period sheaf with connection ${\mathcal O}{\bf B}_{\rm dR,{\rm pd}}^+,d$ on the $v$-site. The authors prove a moduli-level equivalence between Hitchin-small ${\bf B}_{\rm dR,n}^+$-local systems on $X_v$ and Hitchin-small integrable connections on a fixed lifting ${\widetilde X}_n$ of the generic fiber $X$, for all $n\ge 1$, and they establish this via a globally defined period sheaf satisfying a stacky Riemann--Hilbert correspondence. The strategy hinges on local-to-global arguments: a local small Riemann--Hilbert theory (via a local Simpson correspondence for a Gamma-action) combined with exactification of log-structures and chart-independent constructions of the period sheaf, then assembled into a stack-level equivalence. The results extend the non-abelian $p$-adic Hodge theory program to the Hitchin-small locus over a perfectoid base and yield applications to arithmetic RH in good reduction, as well as to moduli problems in $p$-adic geometry and Higgs/bundle correspondences. The framework provides a robust bridge between ${\bf B}_{\rm dR}^+$-local systems and Higgs/flat-connection data in a stack-theoretic setting, with potential further extensions to broader base fields and moduli spaces.
Abstract
Let $C$ be an algebraically closed perfectoid field over $\mathbb{Q}_p$ with the ring of integer $\mathcal{O}_C$ and the infinitesimal thickening $\Ainf$. Let $\mathfrak X$ be a semi-stable formal scheme over $\mathcal{O}_C$ with a fixed flat lifting $\widetilde{\mathfrak X}$ over $\Ainf$. Let $X$ be the generic fiber of $\mathfrak{X}$ and $\widetilde X$ be its lifting over $\BdRp$ induced by $\widetilde{\mathfrak X}$. Let $\MIC_r(\widetilde X)^{{\rm H}\text{-small}}$ and $\rL\rS_r(X,\BBdRp)^{{\rm H}\text{-small}}$ be the $v$-stacks of rank-$r$ Hitchin-small integrable connections on $X_{\et}$ and $\BBdRp$-local systems on $X_{v}$, respectively. In this paper, we establish an equivalence between these two stacks by introducing a new period sheaf with connection $(\calO\bB_{\dR,\pd}^+,\rd)$ on $X_{v}$.
