Convolution and square in abelian groups II
Journal de théorie des nombres de Bordeaux, Tome 38 (2026) no. 2, pp. 355-409

A critical value on an abelian group $G$ of odd order $d$ is a value $\lambda $ such that the functional equation $f\star f (2\,t) =\lambda f(t)^2$ on $G$ has a nonzero solution $f$. We construct many critical values by using abelian varieties with complex multiplication.

Une valeur $\lambda $ est dite critique sur un groupe abélien d’ordre impair $G$ si l’équation fonctionnelle $f\star f (2\,t) =\lambda f(t)^2$ sur $G$ a une solution $f\ne 0$. Nous construisons de nombreuses valeurs critiques à l’aide des variétés abéliennes à multiplication complexe.

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DOI : 10.5802/jtnb.1365
Classification : 11F03, 11F27
Keywords: Functional Equation, Convolution, Abelian variety, Torsion groups, Complex multiplication, Theta functions, Weil number, Modular variety.

Yves Benoist  1

1 CNRS, Université Paris-Saclay, IMO, Bâtiment 307, 91405 Orsay, France
Licence : CC-BY-ND 4.0
Droits d'auteur : Les auteurs conservent leurs droits
Yves Benoist. Convolution and square in abelian groups II. Journal de théorie des nombres de Bordeaux, Tome 38 (2026) no. 2, pp. 355-409. doi: 10.5802/jtnb.1365
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