Pré-Publication, Document De Travail Année : 2024

Torsion bounds for a fixed abelian variety and varying number field

Davide Lombardo
  • Fonction : Auteur
David Zywina
  • Fonction : Auteur

Résumé

Let $A$ be an abelian variety defined over a number field $K$. For a finite extension $L/K$, the cardinality of the group $A(L)_{\operatorname{tors}}$ of torsion points in $A(L)$ can be bounded in terms of the degree $[L:K]$. We study the smallest real number $\beta_A$ such that for any finite extension $L/K$ and $\varepsilon>0$, we have $|A(L)_{\operatorname{tors}}| \leq C \cdot [L:K]^{\beta_A+\varepsilon}$, where the constant $C$ depends only on $A$ and $\varepsilon$ (and not $L$). Assuming the Mumford--Tate conjecture for $A$, we will show that $\beta_A$ agrees with the conjectured value of Hindry and Ratazzi. We also give a similar bound for the maximal order of a torsion point in $A(L)$.

Dates et versions

hal-04788313 , version 1 (18-11-2024)

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Samuel Le Fourn, Davide Lombardo, David Zywina. Torsion bounds for a fixed abelian variety and varying number field. 2024. ⟨hal-04788313⟩
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