Ekedahl-Oort strata under natural embeddings of orthogonal and unitary Shimura varieties

Fuente: arXiv
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Main Authors: Qijun, Yan, Chao, Zhang
Format: Preprint
Published: 2026
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author Qijun, Yan
Chao, Zhang
author_facet Qijun, Yan
Chao, Zhang
contents In this paper, we study the behavior of Ekedahl-Oort strata under natural embeddings between the good reductions modulo $p$ of GSpin Shimura varieties and Rapoport-Smithling-Zhang unitary Shimura varieties, a prototypical setting for the construction of special cycles in the Kudla program. In each case, we determine the EO stratum containing the image of a given EO stratum under the embedding. We also compute discrete invariants of these Shimura varieties, including their $p$-ranks and $a$-numbers; in the GSpin case, these are obtained via the Kuga-Satake embedding.
format Preprint
id arxiv_https___arxiv_org_abs_2605_27207
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Ekedahl-Oort strata under natural embeddings of orthogonal and unitary Shimura varieties
Qijun, Yan
Chao, Zhang
Number Theory
Algebraic Geometry
14G35, 11G18
In this paper, we study the behavior of Ekedahl-Oort strata under natural embeddings between the good reductions modulo $p$ of GSpin Shimura varieties and Rapoport-Smithling-Zhang unitary Shimura varieties, a prototypical setting for the construction of special cycles in the Kudla program. In each case, we determine the EO stratum containing the image of a given EO stratum under the embedding. We also compute discrete invariants of these Shimura varieties, including their $p$-ranks and $a$-numbers; in the GSpin case, these are obtained via the Kuga-Satake embedding.
title Ekedahl-Oort strata under natural embeddings of orthogonal and unitary Shimura varieties
topic Number Theory
Algebraic Geometry
14G35, 11G18
url https://arxiv.org/abs/2605.27207