Integration of Cocycles and Lefschetz Number Formulae for Differential Operators

TL;DR

This paper connects Hochschild cocycles, Lefschetz number formulas, and noncommutative residues to provide new proofs and generalizations of classical theorems in complex geometry and differential operators.

Contribution

It introduces a novel approach linking Hochschild cocycles with Lefschetz numbers and noncommutative residues, extending previous results to arbitrary vector bundles and complex manifolds.

Findings

Lefschetz number expressed as an integral of a constructed form.

Generalization of the Lefschetz number theorem of Engeli-Felder.

Construction of the holomorphic noncommutative residue for arbitrary vector bundles.

Abstract

Let ${\mathcal E}$ be a holomorphic vector bundle on a complex manifold $X$ such that $\dim_{{\mathbb C}}X=n$. Given any continuous, basic Hochschild $2n$-cocycle $\psi_{2n}$ of the algebra ${\rm Diff}_n$ of formal holomorphic differential operators, one obtains a $2n$-form $f_{{\mathcal E},\psi_{2n}}(\mathcal D)$ from any holomorphic differential operator ${\mathcal D}$ on ${\mathcal E}$. We apply our earlier results [J. Noncommut. Geom. 2 (2008), 405-448; J. Noncommut. Geom. 3 (2009), 27-45] to show that $\int_X f_{{\mathcal E},\psi_{2n}}({\mathcal D})$ gives the Lefschetz number of $\mathcal D$ upto a constant independent of $X$ and ${\mathcal E}$. In addition, we obtain a "local" result generalizing the above statement. When $\psi_{2n}$ is the cocycle from [Duke Math. J. 127 (2005), 487-517], we obtain a new proof as well as a generalization of the Lefschetz number theorem of Engeli-Felder. We also obtain an analogous "local" result pertaining to B. Shoikhet's construction of the holomorphic noncommutative residue of a differential operator for trivial vector bundles on complex parallelizable manifolds. This enables us to give a rigorous construction of the holomorphic noncommutative residue of $\mathcal D$ defined by B. Shoikhet when ${\mathcal E}$ is an arbitrary vector bundle on an arbitrary compact complex manifold $X$. Our local result immediately yields a proof of a generalization of Conjecture 3.3 of [Geom. Funct. Anal. 11 (2001), 1096-1124].