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Deformations of cones of primitive vectors

Sebastien Jansou
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Abstract

For 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.

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Sebastien Jansou. 2005-11-22. Deformations of cones of primitive vectors. https://arxiv.org/abs/math/0506133

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