Lifting residual Galois representations with the same semi-simplification

Fuente: arXiv
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Main Author: Nikoloski, Stefan
Format: Preprint
Published: 2025
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author Nikoloski, Stefan
author_facet Nikoloski, Stefan
contents If a $p$-adic Galois representation $ρ_{f,ν}:Γ_{\mathbb Q} \to \GL_2(E_{f,ν})$ attached to some eigenform $f$ is residually reducible it will have 2 non-isomorphic reductions, which have the same semi-simplification. In this paper, we answer a version of the inverse question, first brought up by Toby Gee and Alice Pozzi. Starting with two modulo $p$ non-semi-simple representations $\overline{ρ_1},\overline{ρ_2}:Γ_{\mathbb Q} \to \GL_2(k)$, which have the same semi-simplification we show that under some mild conditions that they are reductions of representations attached to newforms of the same weight $r \ge 2$, the same level $N \ge 1$, and the same Neben character $\varepsilon$.
format Preprint
id arxiv_https___arxiv_org_abs_2506_12644
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lifting residual Galois representations with the same semi-simplification
Nikoloski, Stefan
Number Theory
11F80, 11R39
If a $p$-adic Galois representation $ρ_{f,ν}:Γ_{\mathbb Q} \to \GL_2(E_{f,ν})$ attached to some eigenform $f$ is residually reducible it will have 2 non-isomorphic reductions, which have the same semi-simplification. In this paper, we answer a version of the inverse question, first brought up by Toby Gee and Alice Pozzi. Starting with two modulo $p$ non-semi-simple representations $\overline{ρ_1},\overline{ρ_2}:Γ_{\mathbb Q} \to \GL_2(k)$, which have the same semi-simplification we show that under some mild conditions that they are reductions of representations attached to newforms of the same weight $r \ge 2$, the same level $N \ge 1$, and the same Neben character $\varepsilon$.
title Lifting residual Galois representations with the same semi-simplification
topic Number Theory
11F80, 11R39
url https://arxiv.org/abs/2506.12644