Abelian varieties are de Rham $K(π,1)$

Fuente: arXiv
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Main Authors: Bao, Vo Quoc, Nguyen, Quang-Khai
Format: Preprint
Published: 2026
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_version_ 1866914288610836480
author Bao, Vo Quoc
Nguyen, Quang-Khai
author_facet Bao, Vo Quoc
Nguyen, Quang-Khai
contents Motivated by the work of Esnault-Hai, one has the notion of de Rham $K(π,1)$ schemes, defined as follows. Given a smooth proper geometrically connected scheme $X$ over a field $k$ of characteristic 0 and a base point $x \in X (k)$, one can define its differential fundamental group $π^{\mathrm{diff}}(X/k)$, which comes from the Tannakian duality of the category of coherent integrable connections on $X$. Using the formalism of $δ$-functors, one can define natural morphisms between the group-scheme cohomology of $π^{\mathrm{diff}}(X/k)$ and the de Rham cohomology of $X$. One says that $X$ with $x\in X(k)$ is de Rham $K(π,1)$ if such morphisms are all isomorphisms. In this article, we first prove that abelian varieties in characteristic $0$ are de Rham $K(π,1)$. In the second part of the article, we study the group-scheme cohomology of the abelianization of the differential fundamental group of a smooth proper geometrically connected scheme via its Albanese variety.
format Preprint
id arxiv_https___arxiv_org_abs_2601_01595
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Abelian varieties are de Rham $K(π,1)$
Bao, Vo Quoc
Nguyen, Quang-Khai
Algebraic Geometry
14F40, 14F43, 14L15, 18G15, 18G40, 18M25
Motivated by the work of Esnault-Hai, one has the notion of de Rham $K(π,1)$ schemes, defined as follows. Given a smooth proper geometrically connected scheme $X$ over a field $k$ of characteristic 0 and a base point $x \in X (k)$, one can define its differential fundamental group $π^{\mathrm{diff}}(X/k)$, which comes from the Tannakian duality of the category of coherent integrable connections on $X$. Using the formalism of $δ$-functors, one can define natural morphisms between the group-scheme cohomology of $π^{\mathrm{diff}}(X/k)$ and the de Rham cohomology of $X$. One says that $X$ with $x\in X(k)$ is de Rham $K(π,1)$ if such morphisms are all isomorphisms. In this article, we first prove that abelian varieties in characteristic $0$ are de Rham $K(π,1)$. In the second part of the article, we study the group-scheme cohomology of the abelianization of the differential fundamental group of a smooth proper geometrically connected scheme via its Albanese variety.
title Abelian varieties are de Rham $K(π,1)$
topic Algebraic Geometry
14F40, 14F43, 14L15, 18G15, 18G40, 18M25
url https://arxiv.org/abs/2601.01595