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In this paper, we define the eta cochain form and prove its regularity when the kernel of a family of Dirac operators is a vector bundle. We decompose the eta form as a pairing of the eta cochain form with the Chern character of an…

Differential Geometry · Mathematics 2016-07-21 Yong Wang

This paper is the second part of a series of papers on noncommutative geometry and conformal geometry. In this paper, we compute explicitly the Connes-Chern character of an equivariant Dirac spectral triple. The formula that we obtain for…

Differential Geometry · Mathematics 2017-03-17 Raphael Ponge , Hang Wang

We offer a short proof of Connes' Hochschild class of the Chern character formula for non-unital semifinite spectral triples. The proof is simple due to its reliance on the authors' extensive work on a refined version of the local index…

K-Theory and Homology · Mathematics 2018-05-02 Alan L. Carey , A. Rennie

We prove two geometric index theorems for a family of first-order elliptic operators over a manifold with boundary by computing eta form representatives for the Chern character classes of the index bundle. The eta forms occur as relative…

Differential Geometry · Mathematics 2007-05-23 S. Scott

These notes form the next episode in a series of articles dedicated to a detailed proof of a cohomological index formula for transversally elliptic pseudo-differential operators and applications. The first two chapters are already available…

Differential Geometry · Mathematics 2008-01-21 Paul-Emile Paradan , Michèle Vergne

In this paper, we develope an equivariant theory of Chern characters for coherent sheaves on compact complex manifolds with finite group actions, taking values in Bott-Chern cohomology classes. Furthermore, we establish the corresponding…

Algebraic Geometry · Mathematics 2025-05-28 Guangzhe Xu

In this paper we consider a family of Dirac-type operators on fibration $P \to B$ equivariant with respect to an action of an etale groupoid. Such a family defines an element in the bivariant $K$ theory. We compute the action of the…

Differential Geometry · Mathematics 2007-05-23 Alexander Gorokhovsky

There is a Chern character from K-theory to negative cyclic homology. We show that it preserves the decomposition coming from Adams operations, at least in characteristic 0. This is done by using infinitesimal cohomology to reduce to the…

K-Theory and Homology · Mathematics 2011-08-03 G. Cortiñas , C. Haesemeyer , C. A. Weibel

In 1996, Berline and Vergne gave a cohomological formula for the index of a transversally elliptic operator. In this paper we propose a new point of view where the cohomological formulae make use of equivariant Chern characters with…

Differential Geometry · Mathematics 2008-12-18 Paul-Emile Paradan , Michèle Vergne

If I is a nilpotent ideal in a $\mathbb{Q}$-algebra $A$, Goodwillie defined two isomorphisms from $K_*(A,I)$ to negative cyclic homology, $HN_*(A,I)$. One is the relative version of the absolute Chern character, and the other is defined…

K-Theory and Homology · Mathematics 2011-08-03 Guillermo Cortiñas , Charles Weibel

Let $M^{2n}$ be a unitary torus $(2n)$-manifold, i.e., a $(2n)$-dimensional oriented stable complex connected closed $T^n$-manifold having a nonempty fixed set. In this paper we show that $M$ bounds equivariantly if and only if the…

Algebraic Topology · Mathematics 2012-05-31 Zhi Lü , Qiangbo Tan

In this paper we construct a bivariant Chern character for the equivariant KK-theory of a totally disconnected group with values in bivariant equivariant cohomology in the sense of Baum and Schneider. We prove in particular that the…

K-Theory and Homology · Mathematics 2007-05-23 Christian Voigt

These notes are the first chapter of a monograph, dedicated to a detailed proof of the equivariant index theorem for transversally elliptic operators. In this preliminary chapter, we prove a certain number of natural relations in…

Differential Geometry · Mathematics 2007-12-10 Paul-Emile Paradan , Michèle Vergne

Let $d$ be a positive integer. We study the proportion of irreducible characters of infinite families of irreducible Coxeter groups whose values evaluated on a fixed element $g$ are divisible by $d$. For Coxeter groups of types $A_n, B_n$…

Representation Theory · Mathematics 2025-04-29 Jyotirmoy Ganguly , Rohit Joshi

We construct Chern-Simons bundles as $\mathrm{Aut}^{+}P$-equivariant $U(1)$ -bundles with connection over the space of connections $\mathcal{A}_{P}$ on a principal $G$-bundle $P\rightarrow M$. We show that the Chern-Simons bundles are…

Mathematical Physics · Physics 2021-08-25 Roberto Ferreiro Pérez

Let $M$ be a topological $G_2$-manifold. We prove that the space of infinitesimal associative deformations of a compact associative submanifold $Y$ with boundary in a coassociative submanifold $X$ is the solution space of an elliptic…

Differential Geometry · Mathematics 2010-12-30 Damien Gayet , Frederik Witt

We construct a periodic cyclic cocycle on the symbol algebra of Boutet de Monvel operators and use it to interpret the index formula for elliptic pseudodifferential boundary value problems due to Fedosov as the Chern--Connes pairing of the…

K-Theory and Homology · Mathematics 2023-02-08 A. V. Boltachev , A. Yu. Savin

An odd index theorem for higher odd Chern characters of crossed product algebras is proved. It generalizes the Noether-Gohberg-Krein index theorem. Furthermore, a local formula for the associated cyclic cocycle is provided. When applied to…

Mathematical Physics · Physics 2016-10-27 Emil Prodan , Hermann Schulz-Baldes

We provide a proof of Connes' formula for a representative of the Hochschild class of the Chern character for (p,\infty)-summable spectral triples. Our proof is valid for all semifinite von Neumann algebras, and all integral p\geq 1. We…

Operator Algebras · Mathematics 2007-05-23 A. Carey , J. Phillips , A. Rennie , F. Sukochev

We employ combinatorial techniques to present an explicit formula for the coefficients in front of Chern classes involving in the Hattori-Stong integrability conditions. We also give an evenness condition for the signature of stably…

Differential Geometry · Mathematics 2026-02-25 Ping Li , Wangyang Lin
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