Character values and conductors of low-rank groups of Lie type

Fuente: arXiv
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Autori principali: Herbig, Christopher, Hung, Nguyen N.
Natura: Preprint
Pubblicazione: 2026
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author Herbig, Christopher
Hung, Nguyen N.
author_facet Herbig, Christopher
Hung, Nguyen N.
contents Let $χ$ be a complex irreducible character of a finite group $G$. The conductor of $χ$, denoted $c(χ)$, is the smallest positive integer $n$ such that $χ(x)\in \mathbb{Q}(\exp({2πi/n}))$ for all $x\in G$. We show that for certain rank $1$ finite groups of Lie type, the conductor $c(χ)$ is realized at a single group element; that is, there exists $g\in G$ such that $c(χ)=c(χ(g))$. In some quasisimple cases, we further prove that the field of values \(\mathbb{Q}(χ)\) is generated by a single value. This phenomenon, which is related to a well-known conjecture of W.~Feit, was recently observed by Boltje \emph{et al.} in their reduction of the conjecture to finite simple groups. Our approach uses techniques from algebraic number theory together with the known character tables of these groups.
format Preprint
id arxiv_https___arxiv_org_abs_2604_10888
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Character values and conductors of low-rank groups of Lie type
Herbig, Christopher
Hung, Nguyen N.
Representation Theory
Group Theory
Number Theory
20C15, 11R18, 20C33, 11R20
Let $χ$ be a complex irreducible character of a finite group $G$. The conductor of $χ$, denoted $c(χ)$, is the smallest positive integer $n$ such that $χ(x)\in \mathbb{Q}(\exp({2πi/n}))$ for all $x\in G$. We show that for certain rank $1$ finite groups of Lie type, the conductor $c(χ)$ is realized at a single group element; that is, there exists $g\in G$ such that $c(χ)=c(χ(g))$. In some quasisimple cases, we further prove that the field of values \(\mathbb{Q}(χ)\) is generated by a single value. This phenomenon, which is related to a well-known conjecture of W.~Feit, was recently observed by Boltje \emph{et al.} in their reduction of the conjecture to finite simple groups. Our approach uses techniques from algebraic number theory together with the known character tables of these groups.
title Character values and conductors of low-rank groups of Lie type
topic Representation Theory
Group Theory
Number Theory
20C15, 11R18, 20C33, 11R20
url https://arxiv.org/abs/2604.10888