Conjecture on rational torsion orders for GL2-type abelian varieties

Let A/QA/\mathbb Q be a gg-dimensional abelian variety of GL2\operatorname{GL}_2-type. Its rational torsion subgroup is Tors(A)(Q)\operatorname{Tors}(A)(\mathbb Q).

Torsion-order conjecture. The possible orders Tors(A)(Q)|\operatorname{Tors}(A)(\mathbb Q)| are precisely the integers listed below:

  • If g=2g=2, they are 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20,21,22,24,28,44,561,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20,21,22,24,28,44,56.
  • If g=3g=3, they are 1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,20,22,23,28,29,31,32,40,44,46,58,80,921,2,3,4,5,6,7,8,9,10,11,12,13,14,16,17,20,22,23,28,29,31,32,40,44,46,58,80,92.

The lists are based on computational evidence from predicted torsion orders, and the authors do not know whether they are exhaustive; the conjecture concerns dimensions 22 and 33.

Sources & referencesView supporting material

Primary source

Jessica Alessandrì and Nirvana Coppola, “Torsion points on GL_2-type abelian varieties”, arXiv:2602.21047 (2026).

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