[HG_A] Generic additive character varieties and tensor product multiplicities of generic Deligne–Lusztig characters
ABSTRACT
Computing multiplicities in tensor products of irreducible characters is a natural problem in representation theory. The main goal of this talk is to give a geometric interpretation of the multiplicity of a tensor product of generic Deligne–Lusztig characters. More precisely, we express this multiplicity in terms of point counts of generic additive character varieties associated with isolated pseudo-Levi subgroups. This work is motivated by Letellier’s study of absolutely indecomposable quasi-parabolic bundles. We will also explain how these multiplicities are related to counting absolutely indecomposable quasi-parabolic bundles.
