A Groupoid Approach to the Riemann Integral (and Path Integral Quantization of the Poisson Sigma Model)

Abstract: We use groupoids and the van Est map to define Riemann sums on compact manifolds (with boundary), in a coordinate-free way. These Riemann sums converge to the usual integral after taking a limit over all triangulations of the manifold. We show that the van Est map determines the n-jet of antisymmetric n-cochains. We discuss using this Riemann sum construction to put the Poisson sigma model on a lattice.