dorsal/arxiv
View SchemaReal characters and real classes of $\mathrm{GL}_2$ and $\mathrm{GU}_2$ over discrete valuation rings
| Authors | Archita Gupta, Tejbir Lohan, Pooja Singla |
|---|---|
| Categories | |
| ArXiv ID | 2601.10670vv1 |
| URL | https://arxiv.org/abs/2601.10670 |
| License | http://creativecommons.org/licenses/by/4.0/ |
Abstract
Let $\mathfrak{o}$ be the ring of integers of a non-archimedean local field with residue field of odd characteristic, $\mathfrak{p}$ be its maximal ideal and let $\mathfrak{o}_\ell = \mathfrak{o}/\mathfrak{p}^\ell$ for $\ell\ge 2$. In this article, we study real-valued characters and real representations of the finite groups $\mathrm{GL}_2(\mathfrak{o}_\ell)$ and $\mathrm{GU}_2(\mathfrak{o}_\ell)$. We give a complete classification of real and strongly real classes of these groups and characterize the real-valued irreducible complex characters. We prove that every real-valued irreducible complex character of $\mathrm{GL}_2(\mathfrak{o}_\ell)$ is afforded by a representation over $\mathbb{R}$. In contrast, we show that $\mathrm{GU}_2(\mathfrak{o}_\ell)$ admits real-valued irreducible characters that are not realizable over $\mathbb{R}$. These results extend the parallel known phenomena for the finite groups $\mathrm{GL}_n(\mathbb{F}_q)$ and $\mathrm{GU}_n(\mathbb{F}_q)$.
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"abstract": "Let $\\mathfrak{o}$ be the ring of integers of a non-archimedean local field with residue field of odd characteristic, $\\mathfrak{p}$ be its maximal ideal and let $\\mathfrak{o}_\\ell = \\mathfrak{o}/\\mathfrak{p}^\\ell$ for $\\ell\\ge 2$. In this article, we study real-valued characters and real representations of the finite groups $\\mathrm{GL}_2(\\mathfrak{o}_\\ell)$ and $\\mathrm{GU}_2(\\mathfrak{o}_\\ell)$. We give a complete classification of real and strongly real classes of these groups and characterize the real-valued irreducible complex characters. We prove that every real-valued irreducible complex character of $\\mathrm{GL}_2(\\mathfrak{o}_\\ell)$ is afforded by a representation over $\\mathbb{R}$. In contrast, we show that $\\mathrm{GU}_2(\\mathfrak{o}_\\ell)$ admits real-valued irreducible characters that are not realizable over $\\mathbb{R}$. These results extend the parallel known phenomena for the finite groups $\\mathrm{GL}_n(\\mathbb{F}_q)$ and $\\mathrm{GU}_n(\\mathbb{F}_q)$.",
"arxiv_id": "2601.10670",
"authors": [
"Archita Gupta",
"Tejbir Lohan",
"Pooja Singla"
],
"categories": [
"math.RT",
"math.GR",
"math.RA"
],
"license": "http://creativecommons.org/licenses/by/4.0/",
"title": "Real characters and real classes of $\\mathrm{GL}_2$ and $\\mathrm{GU}_2$ over discrete valuation rings",
"url": "https://arxiv.org/abs/2601.10670",
"version": "v1"
},
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