Modular Classes of Lie Groupoid Representations up to Homotopy
arXiv:1502.06253 · doi:10.3842/SIGMA.2015.058
Abstract
We describe a construction of the modular class associated to a representation up to homotopy of a Lie groupoid. In the case of the adjoint representation up to homotopy, this class is the obstruction to the existence of a volume form, in the sense of Weinstein's "The volume of a differentiable stack".