Automorphisms of Lie groupoids and symplectic reduction on orbifolds

Fuente: arXiv
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Main Authors: Chen, Bohui, Du, Cheng-Yong, Jiang, Fengyu
Format: Preprint
Published: 2026
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author Chen, Bohui
Du, Cheng-Yong
Jiang, Fengyu
author_facet Chen, Bohui
Du, Cheng-Yong
Jiang, Fengyu
contents In this paper, the 2-group BAut(X) of automorphisms of a Lie groupoid X is constructed. Considering the 2-group G action on X, we explain the equivalence between 2-group homomorphisms from G to BAut(X) with Kan fibrations over G with fiber X. This justifies the notion of Kan fibration for 2-group actions on Lie groupoids. As an application, we formulate Hamiltonian actions of étale Lie 2-groups on orbifolds in terms of Kan fibrations and study the symplectic reductions. We show that, in general, the reduction is in fact a symplectic Lie 2-groupoid, and under certain isotropic free condition, the reduction is still an orbifold. Also the slice theorem of a group G action on Lie groupoids is proved.
format Preprint
id arxiv_https___arxiv_org_abs_2605_17351
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Automorphisms of Lie groupoids and symplectic reduction on orbifolds
Chen, Bohui
Du, Cheng-Yong
Jiang, Fengyu
Differential Geometry
Symplectic Geometry
In this paper, the 2-group BAut(X) of automorphisms of a Lie groupoid X is constructed. Considering the 2-group G action on X, we explain the equivalence between 2-group homomorphisms from G to BAut(X) with Kan fibrations over G with fiber X. This justifies the notion of Kan fibration for 2-group actions on Lie groupoids. As an application, we formulate Hamiltonian actions of étale Lie 2-groups on orbifolds in terms of Kan fibrations and study the symplectic reductions. We show that, in general, the reduction is in fact a symplectic Lie 2-groupoid, and under certain isotropic free condition, the reduction is still an orbifold. Also the slice theorem of a group G action on Lie groupoids is proved.
title Automorphisms of Lie groupoids and symplectic reduction on orbifolds
topic Differential Geometry
Symplectic Geometry
url https://arxiv.org/abs/2605.17351