English

Torsion points on $\rm{GL}_2$-type abelian varieties

Number Theory 2026-04-29 v3

Abstract

It is well known that the rational torsion of an abelian variety defined over a number field injects into the reduction modulo any sufficiently large prime, so the order of the torsion group divides the greatest common divisor of the sizes of points on the reduction at each prime. Drawing inspiration from Katz's Inventiones paper (1981), we investigate the converse to this for abelian varieties of GL2\rm GL_2-type and exhibit a conjectural list of possible torsion orders for modular abelian varieties over Q\mathbb Q of dimension up to 55.

Keywords

Cite

@article{arxiv.2602.21047,
  title  = {Torsion points on $\rm{GL}_2$-type abelian varieties},
  author = {Jessica Alessandrì and Nirvana Coppola},
  journal= {arXiv preprint arXiv:2602.21047},
  year   = {2026}
}

Comments

12 pages, comments are welcome! Updated version with conjectures for g up to 5. Github repo: https://github.com/NirvanaC93/Torsion-of-GL2-abelian-varieties

R2 v1 2026-07-01T10:50:16.837Z