2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/101337For a complex connected reductive group G, we classify the simple modules whose cone of primitive vectors admits a nontrivial G-invariant deformation. We relate this classification to that of simple Jordan algebras, and to that (due to Akhiezer) of smooth projective varieties whose orbits under the action of a connected affine algebraic group are a divisor and its complementary. Our main tool is the invariant Hilbert scheme of Alexeev-Brion; we determine the first examples of it. We also determine the infinitesimal deformations (non necessarily G-invariant) of the cones of primitive vectors; they turn out to be trivial for most simple modules.French, 40 pagesAlgebraic GeometryRepresentation Theory14B07 14L30 14M17 17C20 20G05text