On the Lau group scheme

Fuente: arXiv
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Autor principal: Drinfeld, Vladimir
Formato: Preprint
Publicado: 2023
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_version_ 1866915619364929536
author Drinfeld, Vladimir
author_facet Drinfeld, Vladimir
contents In a 2013 article, Eike Lau constructed a canonical morphism from the stack of $n$-truncated Barsotti-Tate groups over $F_p$ to the stack of $n$-truncated displays. He also proved that this morphism is a gerbe banded by a commutative group scheme. In this paper we describe the group scheme explicitly. The stack of $n$-truncated Barsotti-Tate groups over $F_p$ has a generalization related to any pair $(G,μ)$, where $G$ is a smooth group scheme over $Z/p^n$ and $μ$ is a 1-bounded cocharacter of $G$. The same is true for the stack of $n$-truncated displays. We conjecture that in this more general situation the first stack is a gerbe over the second one banded by a commutative group scheme, and we give a conjectural description of this group scheme. We also give a conjectural description of the stack of $n$-truncated Barsotti-Tate groups over the formal spectrum of $Z_p$ and of its $(G,μ)$-generalization.
format Preprint
id arxiv_https___arxiv_org_abs_2307_06194
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the Lau group scheme
Drinfeld, Vladimir
Algebraic Geometry
14L05, 14F30
In a 2013 article, Eike Lau constructed a canonical morphism from the stack of $n$-truncated Barsotti-Tate groups over $F_p$ to the stack of $n$-truncated displays. He also proved that this morphism is a gerbe banded by a commutative group scheme. In this paper we describe the group scheme explicitly. The stack of $n$-truncated Barsotti-Tate groups over $F_p$ has a generalization related to any pair $(G,μ)$, where $G$ is a smooth group scheme over $Z/p^n$ and $μ$ is a 1-bounded cocharacter of $G$. The same is true for the stack of $n$-truncated displays. We conjecture that in this more general situation the first stack is a gerbe over the second one banded by a commutative group scheme, and we give a conjectural description of this group scheme. We also give a conjectural description of the stack of $n$-truncated Barsotti-Tate groups over the formal spectrum of $Z_p$ and of its $(G,μ)$-generalization.
title On the Lau group scheme
topic Algebraic Geometry
14L05, 14F30
url https://arxiv.org/abs/2307.06194