Résumé : We show that the ring of Siegel-Jacobi forms of bounded ratio between weight and index is not finitely generated. Our main tool is the theory of toroidal b-divisors and their relation to convex geometry. As a byproduct of our methods, we prove a conjecture of Kramer about the representation of all Siegel-Jacobi forms as sections of certain line bundles and we recover a formula due to Tai for the asymptotic dimension of the space of Siegel-Jacobi forms of given ratio between weight and index. This is joint work with José Burgos Gil, David Holmes and Robin de Jong.

Mots-Clés : Mixed Shimura varieties; automorphic forms; Chern Weil theory; b-divisors; singular psh metrics