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Bibliographic Details
Main Author: Trias, Justin
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2601.16141
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author Trias, Justin
author_facet Trias, Justin
contents We prove that the Weil representation over a non-archimedean local field can be realised with coefficients in a number field. We give an explicit descent argument to describe precisely which number field the Weil representation descends to. Our methods also apply over more general coefficient fields, such as $\ell$-modular coefficient fields, as well as coefficient rings such as rings of integers i.e. in families. We also prove that the theta correspondence over a perfect field is valid if and only if it is valid over the algebraic closure of this perfect field. These two results together show that the classical local theta correspondence is rational.
format Preprint
id arxiv_https___arxiv_org_abs_2601_16141
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the rationality of the Weil Representation and the local theta correspondence
Trias, Justin
Representation Theory
We prove that the Weil representation over a non-archimedean local field can be realised with coefficients in a number field. We give an explicit descent argument to describe precisely which number field the Weil representation descends to. Our methods also apply over more general coefficient fields, such as $\ell$-modular coefficient fields, as well as coefficient rings such as rings of integers i.e. in families. We also prove that the theta correspondence over a perfect field is valid if and only if it is valid over the algebraic closure of this perfect field. These two results together show that the classical local theta correspondence is rational.
title On the rationality of the Weil Representation and the local theta correspondence
topic Representation Theory
url https://arxiv.org/abs/2601.16141