How an action that stabilizes a bundle gerbe gives rise to a Lie group extension

Fuente: arXiv
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Auteurs principaux: Janssens, Bas, Kristel, Peter
Format: Preprint
Publié: 2024
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author Janssens, Bas
Kristel, Peter
author_facet Janssens, Bas
Kristel, Peter
contents Let $\mathcal{G}$ be a bundle gerbe with connection on a smooth manifold $M$, and let $ρ: G \rightarrow \operatorname{Diff}(M)$ be a smooth action of a Fréchet--Lie group $G$ on $M$ that preserves the isomorphism class of $\mathcal{G}$. In this setting, we obtain an abelian extension of $G$ that consists of pairs $(g,A)$, where $g \in G$, and $A$ is an isomorphism from $ρ_{g}^{*}\mathcal{G}$ to $\mathcal{G}$. We equip this group with a natural structure of abelian Fréchet--Lie group extension of $G$, under the assumption that the first integral homology of $M$ is finitely generated. As an application, we construct the universal central extension (in the category of Fréchet--Lie groups) of the group of Hamiltonian diffeomorphisms of a symplectic surface. As an intermediate step, we obtain a central extension of the group of exact volume-preserving diffeomorphisms of a 3-manifold whose corresponding Lie algebra extension is conjectured to be universal.
format Preprint
id arxiv_https___arxiv_org_abs_2401_13453
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle How an action that stabilizes a bundle gerbe gives rise to a Lie group extension
Janssens, Bas
Kristel, Peter
Differential Geometry
Symplectic Geometry
22E65 (Primary) 22F50, 53C08, 58D05 (Secondary)
Let $\mathcal{G}$ be a bundle gerbe with connection on a smooth manifold $M$, and let $ρ: G \rightarrow \operatorname{Diff}(M)$ be a smooth action of a Fréchet--Lie group $G$ on $M$ that preserves the isomorphism class of $\mathcal{G}$. In this setting, we obtain an abelian extension of $G$ that consists of pairs $(g,A)$, where $g \in G$, and $A$ is an isomorphism from $ρ_{g}^{*}\mathcal{G}$ to $\mathcal{G}$. We equip this group with a natural structure of abelian Fréchet--Lie group extension of $G$, under the assumption that the first integral homology of $M$ is finitely generated. As an application, we construct the universal central extension (in the category of Fréchet--Lie groups) of the group of Hamiltonian diffeomorphisms of a symplectic surface. As an intermediate step, we obtain a central extension of the group of exact volume-preserving diffeomorphisms of a 3-manifold whose corresponding Lie algebra extension is conjectured to be universal.
title How an action that stabilizes a bundle gerbe gives rise to a Lie group extension
topic Differential Geometry
Symplectic Geometry
22E65 (Primary) 22F50, 53C08, 58D05 (Secondary)
url https://arxiv.org/abs/2401.13453