Path components of $\mathrm{G}_2$-moduli spaces may be non-aspherical

Fuente: arXiv
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Hauptverfasser: Crowley, Diarmuid, Goette, Sebastian, Hertl, Thorsten
Format: Preprint
Veröffentlicht: 2025
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author Crowley, Diarmuid
Goette, Sebastian
Hertl, Thorsten
author_facet Crowley, Diarmuid
Goette, Sebastian
Hertl, Thorsten
contents Starting from Joyce's generalised Kummer construction, we exhibit non-trivial families of $\mathrm{G}_2$-manifolds over the two dimensional sphere by resolving singularities with a twisted family of Eguchi-Hanson spaces. We establish that the comparison map $\mathcal{G}_2^{\mathrm{tf}}(M) /\!\!/ \mathrm{Diff}(M)_0 \rightarrow \mathcal{G}_2^{\mathrm{tf}}(M) / \mathrm{Diff}(M)_0$ is a fibration over each path components with Eilenberg Mac Lane spaces as fibres, which allows us to show that these families remain non-trivial in $\mathcal{G}_2^{\mathrm{tf}}(M) / \mathrm{Diff}(M)_0$. In addition, we construct a new invariant based on characteristic classes that allows us to show that different resolutions give rise to different elements in the moduli space.
format Preprint
id arxiv_https___arxiv_org_abs_2503_15829
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Path components of $\mathrm{G}_2$-moduli spaces may be non-aspherical
Crowley, Diarmuid
Goette, Sebastian
Hertl, Thorsten
Geometric Topology
Differential Geometry
55Q52, 57R20 (Primary), 53C29, 57R20, 58D27 (Secondary)
Starting from Joyce's generalised Kummer construction, we exhibit non-trivial families of $\mathrm{G}_2$-manifolds over the two dimensional sphere by resolving singularities with a twisted family of Eguchi-Hanson spaces. We establish that the comparison map $\mathcal{G}_2^{\mathrm{tf}}(M) /\!\!/ \mathrm{Diff}(M)_0 \rightarrow \mathcal{G}_2^{\mathrm{tf}}(M) / \mathrm{Diff}(M)_0$ is a fibration over each path components with Eilenberg Mac Lane spaces as fibres, which allows us to show that these families remain non-trivial in $\mathcal{G}_2^{\mathrm{tf}}(M) / \mathrm{Diff}(M)_0$. In addition, we construct a new invariant based on characteristic classes that allows us to show that different resolutions give rise to different elements in the moduli space.
title Path components of $\mathrm{G}_2$-moduli spaces may be non-aspherical
topic Geometric Topology
Differential Geometry
55Q52, 57R20 (Primary), 53C29, 57R20, 58D27 (Secondary)
url https://arxiv.org/abs/2503.15829