On the geometry of splitting models

Fuente: arXiv
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Hauptverfasser: Bijakowski, S., Zachos, I., Zhao, Z.
Format: Preprint
Veröffentlicht: 2025
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author Bijakowski, S.
Zachos, I.
Zhao, Z.
author_facet Bijakowski, S.
Zachos, I.
Zhao, Z.
contents We consider Shimura varieties associated to a unitary group of signature $(n-s,s)$ where $n$ is even. For these varieties, by using the spin splitting models from Zachos-Zhao, we construct flat, Cohen-Macaulay, and normal $p$-adic integral models with reduced special fiber and with an explicit moduli-theoretic description over odd primes $p$ which ramify in the imaginary quadratic field with level subgroup at $p$ given by the stabilizer of a $π$-modular lattice in the hermitian space. We prove that the special fiber of the corresponding splitting model is stratified by an explicit poset with a combinatorial description, similar to Bijakowski-Hernandez, and we describe its irreducible components. Additionally, we prove the closure relations for this stratification.
format Preprint
id arxiv_https___arxiv_org_abs_2501_05950
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the geometry of splitting models
Bijakowski, S.
Zachos, I.
Zhao, Z.
Number Theory
Algebraic Geometry
We consider Shimura varieties associated to a unitary group of signature $(n-s,s)$ where $n$ is even. For these varieties, by using the spin splitting models from Zachos-Zhao, we construct flat, Cohen-Macaulay, and normal $p$-adic integral models with reduced special fiber and with an explicit moduli-theoretic description over odd primes $p$ which ramify in the imaginary quadratic field with level subgroup at $p$ given by the stabilizer of a $π$-modular lattice in the hermitian space. We prove that the special fiber of the corresponding splitting model is stratified by an explicit poset with a combinatorial description, similar to Bijakowski-Hernandez, and we describe its irreducible components. Additionally, we prove the closure relations for this stratification.
title On the geometry of splitting models
topic Number Theory
Algebraic Geometry
url https://arxiv.org/abs/2501.05950