# Schreiber Higher extensions of diffeomorphism groups

A note that we have written:

• Central extensions of mapping class groups from characteristic classes

Cahiers de Topologie et Géométrie Différentielle Catégoriques

Volume LIX-3, 3ème trimestre 2018

on higher extensions of diffeomorphism groups and central extensions of mapping class groups induced by characteristic classes. This is part of the higher modularity of Local prequantum field theory.

## Abstract

We consider higher extensions of diffeomorphism groups and show how these naturally arise as the group stacks of automorphisms of manifolds that are equipped with higher degree topological structures, such as those appearing in topological field theories. Passing to the groups of connected components, we obtain abelian extensions of mapping class groups and investigate when they are central. As a special case, we obtain in a natural way the $\mathbb{Z}$-central extension needed for the anomaly cancellation of 3d Chern-Simons theory.

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