Families of symplectic Galois representations over small parabolic eigenvarieties for Siegel cuspforms of genus $2$

Fuente: arXiv
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Main Authors: Manji, Muhammad, Thøgersen, Frederick E., Wu, Ju-Feng
Format: Preprint
Published: 2026
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_version_ 1866914492313501696
author Manji, Muhammad
Thøgersen, Frederick E.
Wu, Ju-Feng
author_facet Manji, Muhammad
Thøgersen, Frederick E.
Wu, Ju-Feng
contents We construct small parabolic eigenvarieties for holomorphic Siegel cuspforms of genus $2$ and study families of Galois representations attached to them in the spirit of Bellaïche--Chenevier. In the course, we introduce the notion of $(φ, Γ)$-modules with $G$-structures and the notion of refined families of symplectic Galois representations by implementing the theory of symplectic Galois determinant d'après Moakher--Quast. We then prove an infinitesimal $R=\mathbb{T}$ theorem under mild hypotheses. As an application, we study the relationship between the geometry of the small parabolic eigenvarieties at the Saito--Kurokawa lifts for cuspidal eigenforms (both finite-slope and infinite-slope) and the Bloch--Kato Selmer groups of those eigenforms.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18433
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Families of symplectic Galois representations over small parabolic eigenvarieties for Siegel cuspforms of genus $2$
Manji, Muhammad
Thøgersen, Frederick E.
Wu, Ju-Feng
Number Theory
11F33 11F46, 11F80
We construct small parabolic eigenvarieties for holomorphic Siegel cuspforms of genus $2$ and study families of Galois representations attached to them in the spirit of Bellaïche--Chenevier. In the course, we introduce the notion of $(φ, Γ)$-modules with $G$-structures and the notion of refined families of symplectic Galois representations by implementing the theory of symplectic Galois determinant d'après Moakher--Quast. We then prove an infinitesimal $R=\mathbb{T}$ theorem under mild hypotheses. As an application, we study the relationship between the geometry of the small parabolic eigenvarieties at the Saito--Kurokawa lifts for cuspidal eigenforms (both finite-slope and infinite-slope) and the Bloch--Kato Selmer groups of those eigenforms.
title Families of symplectic Galois representations over small parabolic eigenvarieties for Siegel cuspforms of genus $2$
topic Number Theory
11F33 11F46, 11F80
url https://arxiv.org/abs/2604.18433