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Main Author: Kim, Yoon-Joo
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2410.21193
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author Kim, Yoon-Joo
author_facet Kim, Yoon-Joo
contents Let $π: X \to B$ be a projective Lagrangian fibration of a smooth symplectic variety $X$ to a smooth variety $B$. Denote the complement of the discriminant locus by $B_0 = B \setminus \operatorname{Disc}(π)$, its preimage by $X_0 = π^{-1}(B_0)$, and the complement of the critical locus by $X' = X \setminus \operatorname{Sing}(π)$. Under an assumption that the morphism $X' \to B$ is surjective, we construct (1) the Néron model of the abelian fibration $π_0 : X_0 \to B_0$ and (2) the Néron model of its automorphism abelian scheme $\operatorname{Aut}^{\circ}_{π_0} \to B_0$. Contrary to the case of elliptic fibrations, $X'$ may not be the Néron model of $X_0$; this is precisely because of the existence of flops in higher-dimensional symplectic varieties. Using such techniques, we analyze when $X' \to B$ is a torsor under a smooth group scheme and also revisit some known results in the literature.
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publishDate 2024
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spellingShingle The Néron model of a higher-dimensional Lagrangian fibration
Kim, Yoon-Joo
Algebraic Geometry
Let $π: X \to B$ be a projective Lagrangian fibration of a smooth symplectic variety $X$ to a smooth variety $B$. Denote the complement of the discriminant locus by $B_0 = B \setminus \operatorname{Disc}(π)$, its preimage by $X_0 = π^{-1}(B_0)$, and the complement of the critical locus by $X' = X \setminus \operatorname{Sing}(π)$. Under an assumption that the morphism $X' \to B$ is surjective, we construct (1) the Néron model of the abelian fibration $π_0 : X_0 \to B_0$ and (2) the Néron model of its automorphism abelian scheme $\operatorname{Aut}^{\circ}_{π_0} \to B_0$. Contrary to the case of elliptic fibrations, $X'$ may not be the Néron model of $X_0$; this is precisely because of the existence of flops in higher-dimensional symplectic varieties. Using such techniques, we analyze when $X' \to B$ is a torsor under a smooth group scheme and also revisit some known results in the literature.
title The Néron model of a higher-dimensional Lagrangian fibration
topic Algebraic Geometry
url https://arxiv.org/abs/2410.21193