Dimension growth and Gelfand-Kirillov dimension of representations of quantum groups

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Main Authors: Futorny, Vyacheslav, Liu, Xingpeng
Format: Preprint
Published: 2025
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author Futorny, Vyacheslav
Liu, Xingpeng
author_facet Futorny, Vyacheslav
Liu, Xingpeng
contents We consider two algebraic invariants in the representation theory of quantized enveloping algebras: the dimension growth of simple modules for the De Concini-Kac quantum group at roots of unity, and the Gelfand-Kirillov dimension of simple highest weight modules for the quantum group at generic $q$. In spite of being defined for different values of the parameter $q$, these invariants reflect closely related features in the respective contexts. We show that several new phenomena appear in the quantum case and the representations with non-integral weights contribute to both invariants in a way that cannot be ignored. Building on this, we determine the minimal non-zero value of these invariants for each Lie type. As an application we show that quantum cuspidal modules at generic $q$ can occur only when the underlying semisimple Lie algebra has simple components of type $A$, $B$, or $C$, providing a more explicit representation-theoretic distinction with the classical case.
format Preprint
id arxiv_https___arxiv_org_abs_2512_14385
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dimension growth and Gelfand-Kirillov dimension of representations of quantum groups
Futorny, Vyacheslav
Liu, Xingpeng
Representation Theory
17B37, 17B10 (Primary) 20G42, 16T20 (Secondary)
We consider two algebraic invariants in the representation theory of quantized enveloping algebras: the dimension growth of simple modules for the De Concini-Kac quantum group at roots of unity, and the Gelfand-Kirillov dimension of simple highest weight modules for the quantum group at generic $q$. In spite of being defined for different values of the parameter $q$, these invariants reflect closely related features in the respective contexts. We show that several new phenomena appear in the quantum case and the representations with non-integral weights contribute to both invariants in a way that cannot be ignored. Building on this, we determine the minimal non-zero value of these invariants for each Lie type. As an application we show that quantum cuspidal modules at generic $q$ can occur only when the underlying semisimple Lie algebra has simple components of type $A$, $B$, or $C$, providing a more explicit representation-theoretic distinction with the classical case.
title Dimension growth and Gelfand-Kirillov dimension of representations of quantum groups
topic Representation Theory
17B37, 17B10 (Primary) 20G42, 16T20 (Secondary)
url https://arxiv.org/abs/2512.14385