Schur $σ$-groups of type (3,3)

Fuente: arXiv
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Autore principale: Pink, Richard
Natura: Preprint
Pubblicazione: 2025
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author Pink, Richard
author_facet Pink, Richard
contents For any odd prime $p$, the Galois group of the maximal unramified pro-$p$-extension of an imaginary quadratic field is a Schur $σ$-group. But Schur $σ$-groups can also be constructed and studied abstractly. We prove that if $p>3$, any Schur $σ$-group of Zassenhaus type $(3,3)$, for which every open subgroup has finite abelianization, is isomorphic to an open subgroup of a form of ${\rm PGL}_2$ over ${\mathbb Q}_p$. Combined with earlier work on an analogue of the Cohen-Lenstra heuristic for Schur $σ$-groups, or with the Fontaine-Mazur conjecture, this lends credence to the ``if'' part of a conjecture of McLeman.
format Preprint
id arxiv_https___arxiv_org_abs_2505_05580
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Schur $σ$-groups of type (3,3)
Pink, Richard
Number Theory
11R11 (11R32, 20D15, 20E18, 20F05)
For any odd prime $p$, the Galois group of the maximal unramified pro-$p$-extension of an imaginary quadratic field is a Schur $σ$-group. But Schur $σ$-groups can also be constructed and studied abstractly. We prove that if $p>3$, any Schur $σ$-group of Zassenhaus type $(3,3)$, for which every open subgroup has finite abelianization, is isomorphic to an open subgroup of a form of ${\rm PGL}_2$ over ${\mathbb Q}_p$. Combined with earlier work on an analogue of the Cohen-Lenstra heuristic for Schur $σ$-groups, or with the Fontaine-Mazur conjecture, this lends credence to the ``if'' part of a conjecture of McLeman.
title Schur $σ$-groups of type (3,3)
topic Number Theory
11R11 (11R32, 20D15, 20E18, 20F05)
url https://arxiv.org/abs/2505.05580