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This paper, together with Part II, expands the results of math.DG/9803051. In Part I we study the twisted index theory of elliptic operators on orbifold covering spaces of compact good orbifolds, which are invariant under a projective…

Differential Geometry · Mathematics 2007-05-23 Matilde Marcolli , Varghese Mathai

Using the Arthur-Selberg trace formula we express the index of a Dirac operator on an arithmetic quotient over a totally real field with at least two real embeddings as the integral over the index form plus a sum of orbital integrals. For…

dg-ga · Mathematics 2008-02-03 Anton Deitmar

We introduce the notion of an action of a discrete or compact quantum group on an operator system, and study equivariant operator system injectivity. We then prove a duality result that relates equivariant injectivity with dual injectivity…

Operator Algebras · Mathematics 2024-06-06 Joeri De Ro , Lucas Hataishi

In this note, we give a geometric expression for the multiplicities of the equivariant index of a Dirac operator twisted by a line bundle.

Symplectic Geometry · Mathematics 2014-04-09 Paul-Emile Paradan , Michèle Vergne

In the previous papers, Furuta, Yoshida and the author gave a definition of analytic index theory of Dirac-type operator on open manifolds by making use of some geometric structure on an open covering of the end of the open manifold and a…

Differential Geometry · Mathematics 2015-04-10 Hajime Fujita

We develop notions of twisted spinor bundle and twisted pre-quantum bundle on quasi-Hamiltonian G-spaces. The main result of this paper is that we construct a Dirac operator with index given by positive energy representation of loop group.…

Symplectic Geometry · Mathematics 2016-06-29 Yanli Song

This is an expanded version of the talk I gave at Oberwolfach, MIT and several other universities.

Symplectic Geometry · Mathematics 2007-05-23 Matvei Libine

We define the orbit category for transitive topological groupoids and their equivariant CW-complexes. By using these constructions we define equivariant Bredon homology and cohomology for actions of transitive topological groupoids. We show…

Algebraic Topology · Mathematics 2019-11-11 Carla Farsi , Laura Scull , Jordan Watts

In this note, we study an invariant associated to the zeros of the moment map generated by an action form, the infinitesimal index. This construction will be used to study the compactly supported equivariant cohomology of the zeros of the…

Differential Geometry · Mathematics 2012-03-16 Corrado de Concini , Claudio Procesi , Michele Vergne

We partially describe equivariant Dirac and generalized complex structures on a homogeneous space $G/K$ by giving equivalent data involving only the Lie algebra. We consider real semisimple adjoint orbits in any semisimple Lie algebra over…

Differential Geometry · Mathematics 2010-08-12 Brett Milburn

We generalize the results of a previous paper of ours to compact Lie groups. Using a recently developed ordinary equivariant homology and cohomology, we define equivariant Poincare complexes with the properties that (1) every compact…

Algebraic Topology · Mathematics 2017-06-01 Steven R. Costenoble , Stefan Waner

We construct the coarse index class with support condition (as an element of coarse $K$-homology) of an equivariant Dirac operator on a complete Riemannian manifold endowed with a proper, isometric action of a group. We further show a…

Differential Geometry · Mathematics 2025-05-14 Ulrich Bunke , Alexander Engel

We find and classify possible equivariant spin structures with Dirac operators on the noncommutative torus, proving that similarly as in the classical case the spectrum of the Dirac operator depends on the spin structure.

Quantum Algebra · Mathematics 2018-06-04 Mario Paschke , Andrzej Sitarz

We compute the equivariant local index for the reduced space in a symplectic cut space, provided that the reduced space is compact.

Symplectic Geometry · Mathematics 2016-09-01 Takahiko Yoshida

The goal is to understand the index-theoretic aspects of the recent preprint of R. Nest and F. Radulescu, math.OA/9911042. The basic observation (due to E. Guenter/N. Higson) is that the index of the Toeplitz operator is equal to the index…

Differential Geometry · Mathematics 2007-05-23 U. Bunke

Let $X$ be a locally compact zero-dimensional space, let $S$ be an equicontinuous set of homeomorphisms such that $1 \in S = S^{-1}$, and suppose that $\overline{Gx}$ is compact for each $x \in X$, where $G = \langle S \rangle$. We show in…

Group Theory · Mathematics 2018-07-25 Colin D. Reid

For a finite rank projective bundle over a compact manifold, so associated to a torsion, Dixmier-Douady, 3-class, w, on the manifold, we define the ring of differential operators `acting on sections of the projective bundle' in a formal…

Differential Geometry · Mathematics 2019-10-25 V. Mathai , R. B. Melrose , I. M. Singer

In an earlier article we introduced a new definition for the `quantization' of a Hamiltonian loop group space $\mathcal{M}$, involving the equivariant $L^2$-index of a Dirac-type operator $\mathscr{D}$ on a non-compact finite dimensional…

Symplectic Geometry · Mathematics 2019-12-02 Yiannis Loizides , Yanli Song

Let G be a real reductive Lie group with maximal compact sub- group K. We generalize the usual notion of Dirac index to a twisted version, which is nontrivial even in case G and K do not have equal rank. We compute ordinary and twisted…

Representation Theory · Mathematics 2017-06-27 Dan Barbasch , Pavle Pandzic , Peter Trapa

In the setting of a proper, cocompact action by a locally compact, unimodular group $G$ on a Riemannian manifold, we construct equivariant spectral flow of paths of Dirac-type operators. This takes values in the $K$-theory of the group…

Operator Algebras · Mathematics 2025-02-04 Peter Hochs , Aquerman Yanes