Connes trace theorem for Carnot manifolds
Edward McDonald
TL;DR
This work extends Connes' trace theorem to Carnot manifolds by unifying recent tangent-groupoid–based residues (Dave–Haller and Couchet–Yuncken) and showing that any normalised trace on the weak trace class yields $\varphi(T)=\frac{1}{d_H}\mathrm{Res}(T)$ for $T\in \Psi^{-{d_H}}_H(M)$. The authors develop the van Erp–Yuncken calculus, including the $H$-tangent groupoid, zoom action, local traces, and principal cosymbols, to define and compare the DH and CY residues. They prove that these residues coincide and correspond to the generalized Wodzicki residue in the Carnot setting, with a meromorphic-trace framework via holomorphic families. The results connect spectral Weyl-type asymptotics to residue functionals, extending Connes' trace theorem beyond classical elliptic theory and providing a robust tool for noncommutative geometry on filtered manifolds. This has potential implications for index theory, noncommutative geometry, and spectral geometry on sub-Riemannian and hypoelliptic settings.
Abstract
The Wodzicki residue is the unique trace on the algebra of classical pseudodifferential operators on a closed manifold, and Connes in 1988 proved that it coincides with the Dixmier trace. A Carnot manifold is a manifold $M$ whose tangent bundle $TM$ is equipped with a nested family $H$ of sub-bundles $H_0\leq H_1 \leq \cdots \leq TM$ which defines a filtration of the Lie algebra of vector fields on $M.$ Differential operators on Carnot manifolds have their order measured in terms of the filtration defined by $H,$ and the algebra of differential operators can be extended to an algebra of pseudodifferential operators. Recently, Dave-Haller and Couchet-Yuncken proposed definitions of a residue functional on the algebra of pseudodifferential operators adapted to a Carnot manifold. We prove that Connes' trace theorem holds in this setting.
