On the ramification of modular parametrizations at the cusps
Résumé
We investigate the ramification of modular parametrizations of elliptic curves over $\Q$ at the cusps. We prove that if the modular form associated to the elliptic curve has minimal level among its twists by Dirichlet characters, then the modular parametrization is unramified at the cusps. The proof uses Bushnell's formula for the Godement-Jacquet local constant of a cuspidal automorphic representation of $\GL(2)$. We also report on numerical computations indicating that in general, the ramification index at a cusp seems to be a divisor of 24.
Domaines
Théorie des nombres [math.NT]Origine | Fichiers produits par l'(les) auteur(s) |
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