The modified diagonal cycles of Hypergeometric curves

Fuente: arXiv
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Main Authors: Eskandari, Payman, Nemoto, Yusuke
Format: Preprint
Published: 2025
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author Eskandari, Payman
Nemoto, Yusuke
author_facet Eskandari, Payman
Nemoto, Yusuke
contents For each $N\geq 2$, Asakura and Otsubo have recently introduced a smooth family of algebraic curves $\{X_{N,λ}\}_{λ\in \mathbb{P}^1\setminus \{0, 1, \infty\}}$ in characteristic 0 that is closely related to hypergeometric functions and the Fermat curve of degree $N$. In this paper, we study the Gross-Kudla-Schoen modified diagonal 1-cycles of these curves. We prove that if $p \ge 3$ is a prime, then for every $λ$ the Griffiths Abel-Jacobi image of the modified diagonal cycle of $X_{p,λ}$ is nontrivial for every cuspidal choice of a base point. On the other hand, we show that the modified diagonal cycle and hence the Ceresa cycle of $X_{3,λ}$ is torsion in the Chow group for every $λ$ and every choice of a base point.
format Preprint
id arxiv_https___arxiv_org_abs_2508_06008
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The modified diagonal cycles of Hypergeometric curves
Eskandari, Payman
Nemoto, Yusuke
Algebraic Geometry
Number Theory
14C25, 14F25, 14H40
For each $N\geq 2$, Asakura and Otsubo have recently introduced a smooth family of algebraic curves $\{X_{N,λ}\}_{λ\in \mathbb{P}^1\setminus \{0, 1, \infty\}}$ in characteristic 0 that is closely related to hypergeometric functions and the Fermat curve of degree $N$. In this paper, we study the Gross-Kudla-Schoen modified diagonal 1-cycles of these curves. We prove that if $p \ge 3$ is a prime, then for every $λ$ the Griffiths Abel-Jacobi image of the modified diagonal cycle of $X_{p,λ}$ is nontrivial for every cuspidal choice of a base point. On the other hand, we show that the modified diagonal cycle and hence the Ceresa cycle of $X_{3,λ}$ is torsion in the Chow group for every $λ$ and every choice of a base point.
title The modified diagonal cycles of Hypergeometric curves
topic Algebraic Geometry
Number Theory
14C25, 14F25, 14H40
url https://arxiv.org/abs/2508.06008