Reducibility and rational torsion in modular abelian varieties

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Agashe, Amod, Winters, Matthew
Format: Preprint
Published: 2025
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866908577303625728
author Agashe, Amod
Winters, Matthew
author_facet Agashe, Amod
Winters, Matthew
contents Let N be a square-free positive integer and let f be a newform of weight 2 on Γ_0(N). Let A denote the abelian subvariety of J_0(N) associated to f and let m be a maximal ideal of the Hecke algebra T that contains Ann_T(f) and has residue characteristic r such that r does not divide 6N. We show that if either A[m] or the canonical representation ρ_m over T/m associated to m is reducible, then r divides the order of the cuspidal subgroup of J_0(N) and A[m] has a nontrivial rational point. We mention some applications of this result, including an application to the second part of the Birch and Swinnerton-Dyer conjecture for A.
format Preprint
id arxiv_https___arxiv_org_abs_2510_04323
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Reducibility and rational torsion in modular abelian varieties
Agashe, Amod
Winters, Matthew
Number Theory
Numerical Analysis
Let N be a square-free positive integer and let f be a newform of weight 2 on Γ_0(N). Let A denote the abelian subvariety of J_0(N) associated to f and let m be a maximal ideal of the Hecke algebra T that contains Ann_T(f) and has residue characteristic r such that r does not divide 6N. We show that if either A[m] or the canonical representation ρ_m over T/m associated to m is reducible, then r divides the order of the cuspidal subgroup of J_0(N) and A[m] has a nontrivial rational point. We mention some applications of this result, including an application to the second part of the Birch and Swinnerton-Dyer conjecture for A.
title Reducibility and rational torsion in modular abelian varieties
topic Number Theory
Numerical Analysis
url https://arxiv.org/abs/2510.04323