Local fields, iterated extensions, and Julia Sets

Fuente: arXiv
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Main Authors: Lee, Pui Hang, Manes, Michelle, Truong, Nha Xuan
Format: Preprint
Published: 2025
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author Lee, Pui Hang
Manes, Michelle
Truong, Nha Xuan
author_facet Lee, Pui Hang
Manes, Michelle
Truong, Nha Xuan
contents Let $K$ be a field complete with respect to a discrete valuation $v$ of residue characteristic $p$. For $α\in K$, let $K_\infty$ be the extension obtained by adjoining all iterated preimages of $α$ under a unicritical polynomial $f_c(z)=z^\ell - c \in K[z]$. We study the extension $K_\infty/K$ and show that its qualitative behavior depends only on the valuation of $c$. This removes the previous restrictions on $\ell$ in work of Anderson--Hamblen--Poonen--Walton and completes the classification for all $\ell \ge 2$. We also relate the ramification to the structure of the Berkovich Julia set of $f_c$.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17961
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Local fields, iterated extensions, and Julia Sets
Lee, Pui Hang
Manes, Michelle
Truong, Nha Xuan
Number Theory
Dynamical Systems
11S82, 37P05, 37P20, 37P40
Let $K$ be a field complete with respect to a discrete valuation $v$ of residue characteristic $p$. For $α\in K$, let $K_\infty$ be the extension obtained by adjoining all iterated preimages of $α$ under a unicritical polynomial $f_c(z)=z^\ell - c \in K[z]$. We study the extension $K_\infty/K$ and show that its qualitative behavior depends only on the valuation of $c$. This removes the previous restrictions on $\ell$ in work of Anderson--Hamblen--Poonen--Walton and completes the classification for all $\ell \ge 2$. We also relate the ramification to the structure of the Berkovich Julia set of $f_c$.
title Local fields, iterated extensions, and Julia Sets
topic Number Theory
Dynamical Systems
11S82, 37P05, 37P20, 37P40
url https://arxiv.org/abs/2501.17961