Monodromy groups and exceptional Hodge classes, I: Fermat Jacobians

Fuente: arXiv
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Main Authors: Gallese, Andrea, Goodson, Heidi, Lombardo, Davide
Format: Preprint
Published: 2024
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author Gallese, Andrea
Goodson, Heidi
Lombardo, Davide
author_facet Gallese, Andrea
Goodson, Heidi
Lombardo, Davide
contents Denote by $J_m$ the Jacobian variety of the hyperelliptic curve defined by the affine equation $y^2=x^m+1$ over $\mathbb{Q}$, where $m \geq 3$ is a fixed positive integer. We compute several interesting arithmetic invariants of $J_m$: its decomposition up to isogeny into simple abelian varieties, the minimal field $\mathbb{Q}(\operatorname{End}(J_m))$ over which its endomorphisms are defined, and its connected monodromy field $\mathbb{Q}(\varepsilon_{J_m})$. Currently, there is no general algorithm that computes the last invariant. For large enough values of $m$, the abelian varieties $J_m$ provide non-trivial examples of high-dimensional phenomena, such as degeneracy and the non-triviality of the extension $\mathbb{Q}(\varepsilon_{J_m})/\mathbb{Q}(\operatorname{End}(J_m))$.
format Preprint
id arxiv_https___arxiv_org_abs_2405_20394
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Monodromy groups and exceptional Hodge classes, I: Fermat Jacobians
Gallese, Andrea
Goodson, Heidi
Lombardo, Davide
Number Theory
Algebraic Geometry
11F80, 11G10, 14C25
Denote by $J_m$ the Jacobian variety of the hyperelliptic curve defined by the affine equation $y^2=x^m+1$ over $\mathbb{Q}$, where $m \geq 3$ is a fixed positive integer. We compute several interesting arithmetic invariants of $J_m$: its decomposition up to isogeny into simple abelian varieties, the minimal field $\mathbb{Q}(\operatorname{End}(J_m))$ over which its endomorphisms are defined, and its connected monodromy field $\mathbb{Q}(\varepsilon_{J_m})$. Currently, there is no general algorithm that computes the last invariant. For large enough values of $m$, the abelian varieties $J_m$ provide non-trivial examples of high-dimensional phenomena, such as degeneracy and the non-triviality of the extension $\mathbb{Q}(\varepsilon_{J_m})/\mathbb{Q}(\operatorname{End}(J_m))$.
title Monodromy groups and exceptional Hodge classes, I: Fermat Jacobians
topic Number Theory
Algebraic Geometry
11F80, 11G10, 14C25
url https://arxiv.org/abs/2405.20394