Non-vanishing of Ceresa and Gross--Kudla--Schoen cycles associated to modular curves

Fuente: arXiv
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Main Authors: Kerr, Matt, Li, Wanlin, Qiu, Congling, Yang, Tonghai
Format: Preprint
Published: 2024
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author Kerr, Matt
Li, Wanlin
Qiu, Congling
Yang, Tonghai
author_facet Kerr, Matt
Li, Wanlin
Qiu, Congling
Yang, Tonghai
contents Associated to an algebraic curve $X$, there are two canonically constructed homologically trivial algebraic $1$-cycles, the Ceresa cycle in the Jacobian of $X$, and the Gross-Kudla-Schoen modified diagonal cycle in the triple product $X \times X \times X$. By a result of Shou-Wu Zhang, one is torsion if and only if the other is. In this paper, we prove that these two cycles associated to a large family of modular curves are non-torsion in the corresponding Chow groups. We obtain the result by relating this problem to the study of special cycles on orthogonal Shimura varieties. As the main ingredient and a result of independent interest, we develop a pullback formula for special divisors on modular curves embedded in their products via the diagonal map.
format Preprint
id arxiv_https___arxiv_org_abs_2407_20998
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-vanishing of Ceresa and Gross--Kudla--Schoen cycles associated to modular curves
Kerr, Matt
Li, Wanlin
Qiu, Congling
Yang, Tonghai
Algebraic Geometry
Number Theory
Primary 14C25, Secondary 14G35
Associated to an algebraic curve $X$, there are two canonically constructed homologically trivial algebraic $1$-cycles, the Ceresa cycle in the Jacobian of $X$, and the Gross-Kudla-Schoen modified diagonal cycle in the triple product $X \times X \times X$. By a result of Shou-Wu Zhang, one is torsion if and only if the other is. In this paper, we prove that these two cycles associated to a large family of modular curves are non-torsion in the corresponding Chow groups. We obtain the result by relating this problem to the study of special cycles on orthogonal Shimura varieties. As the main ingredient and a result of independent interest, we develop a pullback formula for special divisors on modular curves embedded in their products via the diagonal map.
title Non-vanishing of Ceresa and Gross--Kudla--Schoen cycles associated to modular curves
topic Algebraic Geometry
Number Theory
Primary 14C25, Secondary 14G35
url https://arxiv.org/abs/2407.20998