Massey products in the étale cohomology of number fields

Fuente: arXiv
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Autori principali: Ahlqvist, Eric, Carlson, Magnus
Natura: Preprint
Pubblicazione: 2022
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author Ahlqvist, Eric
Carlson, Magnus
author_facet Ahlqvist, Eric
Carlson, Magnus
contents We give formulas for 3-fold Massey products in the étale cohomology of the ring of integers of a number field and use these to find the first known examples of imaginary quadratic fields with class group of $p$-rank two possessing an infinite $p$-class field tower, where $p$ is an odd prime. Furthermore, a necessary and sufficient condition, in terms of class groups of $p$-extensions, for the vanishing of 3-fold Massey products is given. As a consequence, we give an elementary and sufficient condition for the infinitude of class field towers of imaginary quadratic fields. We also disprove McLeman's $(3,3)$-conjecture. Lastly, we relate the vanishing of Massey products to the existence of Galois representations of $G_{\mathbb{Q},S}$ which realize an unexpectedly large class group for certain extensions of a quadratic imaginary number field.
format Preprint
id arxiv_https___arxiv_org_abs_2207_06353
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Massey products in the étale cohomology of number fields
Ahlqvist, Eric
Carlson, Magnus
Number Theory
Algebraic Geometry
11R34, 14F20, 14G25
We give formulas for 3-fold Massey products in the étale cohomology of the ring of integers of a number field and use these to find the first known examples of imaginary quadratic fields with class group of $p$-rank two possessing an infinite $p$-class field tower, where $p$ is an odd prime. Furthermore, a necessary and sufficient condition, in terms of class groups of $p$-extensions, for the vanishing of 3-fold Massey products is given. As a consequence, we give an elementary and sufficient condition for the infinitude of class field towers of imaginary quadratic fields. We also disprove McLeman's $(3,3)$-conjecture. Lastly, we relate the vanishing of Massey products to the existence of Galois representations of $G_{\mathbb{Q},S}$ which realize an unexpectedly large class group for certain extensions of a quadratic imaginary number field.
title Massey products in the étale cohomology of number fields
topic Number Theory
Algebraic Geometry
11R34, 14F20, 14G25
url https://arxiv.org/abs/2207.06353