Morita equivalences of vector bundles

TL;DR

This paper develops a Morita invariance framework for vector bundles over Lie groupoids, linking their cohomology and derived categories, with applications to Poisson geometry and representations up to homotopy.

Contribution

It introduces a fundamental theorem characterizing VB-Morita maps, proves Morita invariance of VB-cohomology, and establishes the derived category of VB-groupoids as a Morita invariant.

Findings

VB-cohomology is Morita invariant.

The derived category of VB-groupoids is Morita invariant.

Applications to Poisson geometry and representations up to homotopy.

Abstract

We study vector bundles over Lie groupoids, known as VB-groupoids, and their induced geometric objects over differentiable stacks. We establish a fundamental theorem that characterizes VB-Morita maps in terms of fiber and basic data, and use it to prove the Morita invariance of VB-cohomology, with implications to deformation cohomology of Lie groupoids and of classic geometries. We discuss applications of our theory to Poisson geometry, providing a new insight over Marsden-Weinstein reduction and the integration of Dirac structures. We conclude by proving that the derived category of VB-groupoids is a Morita invariant, which leads to a notion of VB-stacks, and solves (an instance of) an open question on representations up to homotopy.