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Autores principales: Ambrosio, Filippo, Carnovale, Giovanna, Esposito, Francesco, Saunders, Neil, Topley, Lewis
Formato: Preprint
Publicado: 2026
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Acceso en línea:https://arxiv.org/abs/2602.02404
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author Ambrosio, Filippo
Carnovale, Giovanna
Esposito, Francesco
Saunders, Neil
Topley, Lewis
author_facet Ambrosio, Filippo
Carnovale, Giovanna
Esposito, Francesco
Saunders, Neil
Topley, Lewis
contents Kato developed an exotic Deligne-Langlands correspondence using a geometric model for the multiparameter affine Hecke algebra of type C, based on his exotic nilpotent cone. Achar-Henderson and Springer showed that this exotic nilpotent is intimately related to another, apparently simpler variety called the enhanced nilpotent cone. Each of these is defined as the Hilbert nullcone of a polar module, the exotic Sp(2n)-module and the enhanced GL(n)-module, respectively. In this paper we conduct a detailed study of the geometry of these two modules, by introducing the Jordan stratification, simultaneously generalising classical results on the adjoint representation as well as the symmetric space associated to (gl(2n), sp(2n)). One of the key tools we develop is the theory of induced orbits in the enhanced and exotic nilpotent cones, following the work of Lusztig-Spaltenstein. Our main application is a classification of sheets in these modules, inspired by a theorem of Borho.
format Preprint
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Sheets, Jordan classes and induced orbits in the exotic and enhanced modules
Ambrosio, Filippo
Carnovale, Giovanna
Esposito, Francesco
Saunders, Neil
Topley, Lewis
Representation Theory
Algebraic Geometry
Kato developed an exotic Deligne-Langlands correspondence using a geometric model for the multiparameter affine Hecke algebra of type C, based on his exotic nilpotent cone. Achar-Henderson and Springer showed that this exotic nilpotent is intimately related to another, apparently simpler variety called the enhanced nilpotent cone. Each of these is defined as the Hilbert nullcone of a polar module, the exotic Sp(2n)-module and the enhanced GL(n)-module, respectively. In this paper we conduct a detailed study of the geometry of these two modules, by introducing the Jordan stratification, simultaneously generalising classical results on the adjoint representation as well as the symmetric space associated to (gl(2n), sp(2n)). One of the key tools we develop is the theory of induced orbits in the enhanced and exotic nilpotent cones, following the work of Lusztig-Spaltenstein. Our main application is a classification of sheets in these modules, inspired by a theorem of Borho.
title Sheets, Jordan classes and induced orbits in the exotic and enhanced modules
topic Representation Theory
Algebraic Geometry
url https://arxiv.org/abs/2602.02404