Siegel modular forms associated to Weil representations

Fuente: arXiv
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Main Author: Wang, Chun-Hui
Format: Preprint
Published: 2025
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author Wang, Chun-Hui
author_facet Wang, Chun-Hui
contents We study some explicit Siegel modular forms from Weil representations. For the classical theta group $Γ_m(1,2)$ with $m > 1$, there are some eighth roots of unity associated with these modular forms, as noted in the works of Andrianov, Friedberg, Maloletkin, Stark, Styer, Richter, and others. We apply $2$-cocycles introduced by Rao, Kudla, Perrin, Lion-Vergne, Satake-Takase to investigate these unities. We extend our study to the full Siegel group $\operatorname{Sp}_{2m}(\mathbb{Z})$ and obtain two matrix-valued Siegel modular forms from Weil representations; these forms arise from a finite-dimensional representation $\operatorname{Ind}_{\widetildeΓ'_m(1,2)}^{\widetilde{\operatorname{Sp}}'_{2m}(\mathbb{Z})} (1_{Γ_m(1,2)} \cdot \operatorname{Id}_{μ_8})^{-1}$, which is related to Igusa's quotient group $\tfrac{\operatorname{Sp}_{2m}(\mathbb{Z})}{Γ_m(4,8)}$.
format Preprint
id arxiv_https___arxiv_org_abs_2501_12140
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Siegel modular forms associated to Weil representations
Wang, Chun-Hui
Number Theory
Representation Theory
We study some explicit Siegel modular forms from Weil representations. For the classical theta group $Γ_m(1,2)$ with $m > 1$, there are some eighth roots of unity associated with these modular forms, as noted in the works of Andrianov, Friedberg, Maloletkin, Stark, Styer, Richter, and others. We apply $2$-cocycles introduced by Rao, Kudla, Perrin, Lion-Vergne, Satake-Takase to investigate these unities. We extend our study to the full Siegel group $\operatorname{Sp}_{2m}(\mathbb{Z})$ and obtain two matrix-valued Siegel modular forms from Weil representations; these forms arise from a finite-dimensional representation $\operatorname{Ind}_{\widetildeΓ'_m(1,2)}^{\widetilde{\operatorname{Sp}}'_{2m}(\mathbb{Z})} (1_{Γ_m(1,2)} \cdot \operatorname{Id}_{μ_8})^{-1}$, which is related to Igusa's quotient group $\tfrac{\operatorname{Sp}_{2m}(\mathbb{Z})}{Γ_m(4,8)}$.
title Siegel modular forms associated to Weil representations
topic Number Theory
Representation Theory
url https://arxiv.org/abs/2501.12140