Cuspidal endo-support and strong beta extensions

Fuente: arXiv
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Auteurs principaux: Helm, David, Kurinczuk, Robert, Skodlerack, Daniel, Stevens, Shaun
Format: Preprint
Publié: 2026
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author Helm, David
Kurinczuk, Robert
Skodlerack, Daniel
Stevens, Shaun
author_facet Helm, David
Kurinczuk, Robert
Skodlerack, Daniel
Stevens, Shaun
contents Let $G$ be an inner form of a general linear group or classical group over a non-archimedean local field of residual characteristic $p$, assumed odd in the classical case. We prove that every smooth representation of $G$ over an algebraically closed field $R$ of characteristic $\ell\neq p$ contains a maximal semisimple character, i.e., one for which the point in the building of the corresponding centralizer is a vertex. Further, for every endo-parameter adapted to $G$, we define its support, which leads also to the notion of cuspidal endo-support of an irreducible representation, and we relate this to its cuspidal support. We also introduce beta extensions for strong facets in the building of a centralizer, and show these are sufficient for the construction of types. These results are used in a subsequent paper to decompose the category of smooth $R$-representations of $G$.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01781
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Cuspidal endo-support and strong beta extensions
Helm, David
Kurinczuk, Robert
Skodlerack, Daniel
Stevens, Shaun
Representation Theory
Let $G$ be an inner form of a general linear group or classical group over a non-archimedean local field of residual characteristic $p$, assumed odd in the classical case. We prove that every smooth representation of $G$ over an algebraically closed field $R$ of characteristic $\ell\neq p$ contains a maximal semisimple character, i.e., one for which the point in the building of the corresponding centralizer is a vertex. Further, for every endo-parameter adapted to $G$, we define its support, which leads also to the notion of cuspidal endo-support of an irreducible representation, and we relate this to its cuspidal support. We also introduce beta extensions for strong facets in the building of a centralizer, and show these are sufficient for the construction of types. These results are used in a subsequent paper to decompose the category of smooth $R$-representations of $G$.
title Cuspidal endo-support and strong beta extensions
topic Representation Theory
url https://arxiv.org/abs/2604.01781