The Pontryagin Class for Pre-Courant Algebroids

TL;DR

This paper introduces the Pontryagin class for pre-Courant algebroids, characterizing the obstruction to deforming them into Courant algebroids, and explores associated algebraic structures and examples.

Contribution

It defines the Pontryagin class for pre-Courant algebroids and establishes isomorphisms between related algebraic structures under deformation.

Findings

The Jacobiator is naturally closed in pre-Courant algebroids.

The Pontryagin class measures the obstruction to deformation.

Constructed isomorphic Leibniz and Lie 2-algebras for these structures.

Abstract

In this paper, we show that the Jacobiator $J$ of a pre-Courant algebroid is closed naturally. The corresponding equivalence class $[J^\flat]$ is defined as the Pontryagin class, which is the obstruction of a pre-Courant algebroid to be deformed into a Courant algebroid. We construct a Leibniz 2-algebra and a Lie 2-algebra associated to a pre-Courant algebroid and prove that these algebraic structures are isomorphic under deformations. Finally, we introduce the twisted action of a Lie algebra on a manifold to give more examples of pre-Courant algebroids, which include the Cartan geometry.