Descent properties for an abelian variety with extended Galois representation

Fuente: arXiv
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Main Author: Felder, Ludovic
Format: Preprint
Published: 2026
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_version_ 1866915778159181824
author Felder, Ludovic
author_facet Felder, Ludovic
contents Let $K$ be a field, $L$ a finite Galois extension of $K$, and $X$ an abelian variety defined over $L$. If $X$ is isogenous over $L$ to an abelian variety defined over $K$, then the $\ell$-adic Galois representations associated to $X$ extend to representations $\barρ_{\ell,X}:\mathrm{Gal}(\bar{L}/K)\to\mathrm{Aut}(V_\ell X)$ for every prime $\ell$. This paper aims to show that the converse is true for abelian varieties of Type I, with some supplementary conditions needed on the endomorphisms of $X$, when $L$ is either a number field or a function field of prime characteristic different from $2$.
format Preprint
id arxiv_https___arxiv_org_abs_2602_05834
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Descent properties for an abelian variety with extended Galois representation
Felder, Ludovic
Number Theory
Algebraic Geometry
11R34, 11R80, 11G10, 14K15
Let $K$ be a field, $L$ a finite Galois extension of $K$, and $X$ an abelian variety defined over $L$. If $X$ is isogenous over $L$ to an abelian variety defined over $K$, then the $\ell$-adic Galois representations associated to $X$ extend to representations $\barρ_{\ell,X}:\mathrm{Gal}(\bar{L}/K)\to\mathrm{Aut}(V_\ell X)$ for every prime $\ell$. This paper aims to show that the converse is true for abelian varieties of Type I, with some supplementary conditions needed on the endomorphisms of $X$, when $L$ is either a number field or a function field of prime characteristic different from $2$.
title Descent properties for an abelian variety with extended Galois representation
topic Number Theory
Algebraic Geometry
11R34, 11R80, 11G10, 14K15
url https://arxiv.org/abs/2602.05834