Enumerating Galois extensions of number fields

Fuente: arXiv
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Autore principale: Oliver, Robert J. Lemke
Natura: Preprint
Pubblicazione: 2024
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author Oliver, Robert J. Lemke
author_facet Oliver, Robert J. Lemke
contents Let $k$ be a number field. We provide an asymptotic formula for the number of Galois extensions of $k$ with absolute discriminant bounded by some $X \geq 1$, as $X\to\infty$. We also provide an asymptotic formula for the closely related count of extensions $K/k$ whose normal closure has discriminant bounded by $X$. The key behind these results is a new upper bound on the number of Galois extensions of $k$ with a given Galois group $G$ and discriminant bounded by $X$; we show the number of such extensions is $O_{[k:\mathbb{Q}],G} (X^{ \frac{4}{\sqrt{|G|}}})$. This improves over the previous best bound $O_{k,G,ε}(X^{\frac{3}{8}+ε})$ due to Ellenberg and Venkatesh. In particular, ours is the first bound for general $G$ with an exponent that decays as $|G| \to \infty$.
format Preprint
id arxiv_https___arxiv_org_abs_2406_04033
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Enumerating Galois extensions of number fields
Oliver, Robert J. Lemke
Number Theory
Group Theory
Let $k$ be a number field. We provide an asymptotic formula for the number of Galois extensions of $k$ with absolute discriminant bounded by some $X \geq 1$, as $X\to\infty$. We also provide an asymptotic formula for the closely related count of extensions $K/k$ whose normal closure has discriminant bounded by $X$. The key behind these results is a new upper bound on the number of Galois extensions of $k$ with a given Galois group $G$ and discriminant bounded by $X$; we show the number of such extensions is $O_{[k:\mathbb{Q}],G} (X^{ \frac{4}{\sqrt{|G|}}})$. This improves over the previous best bound $O_{k,G,ε}(X^{\frac{3}{8}+ε})$ due to Ellenberg and Venkatesh. In particular, ours is the first bound for general $G$ with an exponent that decays as $|G| \to \infty$.
title Enumerating Galois extensions of number fields
topic Number Theory
Group Theory
url https://arxiv.org/abs/2406.04033