Arithmetic descent of specializations of Galois covers
Abstract
Given a -Galois branched cover of the projective line over a number field , we study whether there exists a closed point of with a connected fiber such that the -Galois field extension induced by specialization "arithmetically descends" to (i.e., there exists a -Galois field extension of whose compositum with the residue field of the point is equal to the specialization). We prove that the answer is frequently positive (whenever is regularly realizable over ) if one first allows a base change to a finite extension of . If one does not allow base change, we prove that the answer is positive when is cyclic. Furthermore, we provide an explicit example of a Galois branched cover of with no -rational points of arithmetic descent.
Keywords
Cite
@article{arxiv.1412.1682,
title = {Arithmetic descent of specializations of Galois covers},
author = {Ryan Eberhart and Hilaf Hasson},
journal= {arXiv preprint arXiv:1412.1682},
year = {2023}
}
Comments
Fixed a typo in the last paragraph of Section 1