An Exploration of Degeneracy in Abelian Varieties of Fermat Type

Fuente: arXiv
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Main Author: Goodson, Heidi
Format: Preprint
Published: 2022
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author Goodson, Heidi
author_facet Goodson, Heidi
contents The term degenerate is used to describe abelian varieties whose Hodge rings contain exceptional cycles -- Hodge cycles that are not generated by divisor classes. We can see the effect of the exceptional cycles on the structure of an abelian variety through its Mumford-Tate group, Hodge group, and Sato-Tate group. In this article we examine degeneracy through these different but related lenses. We specialize to a family of abelian varieties of Fermat type, namely Jacobians of hyperelliptic curves of the form $y^2=x^m-1$. We prove that the Jacobian of the curve is degenerate whenever $m$ is an odd, composite integer. We explore the various forms of degeneracy for several examples, each illustrating different phenomena that can occur.
format Preprint
id arxiv_https___arxiv_org_abs_2211_03909
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle An Exploration of Degeneracy in Abelian Varieties of Fermat Type
Goodson, Heidi
Number Theory
Algebraic Geometry
11G10, 14C30, 11F80, 14K22
The term degenerate is used to describe abelian varieties whose Hodge rings contain exceptional cycles -- Hodge cycles that are not generated by divisor classes. We can see the effect of the exceptional cycles on the structure of an abelian variety through its Mumford-Tate group, Hodge group, and Sato-Tate group. In this article we examine degeneracy through these different but related lenses. We specialize to a family of abelian varieties of Fermat type, namely Jacobians of hyperelliptic curves of the form $y^2=x^m-1$. We prove that the Jacobian of the curve is degenerate whenever $m$ is an odd, composite integer. We explore the various forms of degeneracy for several examples, each illustrating different phenomena that can occur.
title An Exploration of Degeneracy in Abelian Varieties of Fermat Type
topic Number Theory
Algebraic Geometry
11G10, 14C30, 11F80, 14K22
url https://arxiv.org/abs/2211.03909