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Related papers: A Lorentzian Equivariant Index Theorem

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In this expository paper, we explain a formula for the multiplicities of the index of an equivariant transversally elliptic operator on a $G$-manifold. The formula is a sum of integrals over blowups of the strata of the group action and…

Differential Geometry · Mathematics 2021-01-28 Jochen Brüning , Franz W. Kamber , Ken Richardson

We prove a formula for the multiplicities of the index of an equivariant transversally elliptic operator on a $G$-manifold. The formula is a sum of integrals over blowups of the strata of the group action and also involves eta invariants of…

Differential Geometry · Mathematics 2010-07-21 Jochen Bruening , Franz Kamber , Ken Richardson

We present examples of equivariant noncommutative Lorentzian spectral geometries. The equivariance with respect to a compact isometry group (or quantum group) allows to construct the algebraic data of a version of spectral triple geometry…

Mathematical Physics · Physics 2007-05-23 Mario Paschke , Andrzej Sitarz

Equivariant indices have previously been defined in cases where either the group or the orbit space in question is compact. In this paper, we develop an equivariant index without assuming the group or the orbit space to be compact. This…

K-Theory and Homology · Mathematics 2016-09-06 Peter Hochs , Yanli Song

We show that the Dirac operator on a compact globally hyperbolic Lorentzian spacetime with spacelike Cauchy boundary is a Fredholm operator if appropriate boundary conditions are imposed. We prove that the index of this operator is given by…

Differential Geometry · Mathematics 2019-10-01 Christian Baer , Alexander Strohmaier

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

We study two special cases of the equivariant index defined in part I of this series. We apply this index to deformations of Spin$^c$-Dirac operators, invariant under actions by possibly noncompact groups, with possibly noncompact orbit…

Differential Geometry · Mathematics 2016-03-11 Peter Hochs , Yanli Song

We define an equivariant index of Spin$^c$-Dirac operators on possibly noncompact manifolds, acted on by compact, connected Lie groups. The main result in this paper is that the index decomposes into irreducible representations according to…

Differential Geometry · Mathematics 2017-10-18 Peter Hochs , Yanli Song

In this paper we prove a formula for the analytic index of a basic Dirac-type operator on a Riemannian foliation, solving a problem that has been open for many years. We also consider more general indices given by twisting the basic Dirac…

Differential Geometry · Mathematics 2021-01-28 Jochen Brüning , Franz W. Kamber , Ken Richardson

We express the index of the Dirac operator on symplectic quotients of a Hamiltonian loop group manifold with proper moment map in terms of fixed point data.

Symplectic Geometry · Mathematics 2007-05-23 Anton Alekseev , Eckhard Meinrenken , Chris Woodward

In the first part of this series, we defined an equivariant index without assuming the group acting or the orbit space of the action to be compact. This allowed us to generalise an index of deformed Dirac operators, defined for compact…

K-Theory and Homology · Mathematics 2016-02-10 Peter Hochs , Yanli Song

We derive a formula for the eta invariants of equivariant Dirac operators on quotients of compact Lie groups, and for their infinitesimally equivariant extension. As an example, we give some computations for spheres.

Differential Geometry · Mathematics 2009-06-03 S. Goette

We study equivariant families of Dirac operators on the source fibers of a Lie groupoid with a closed space of units and equipped with an action of an auxiliary compact Lie group. We use the Getzler rescaling method to derive a fixed-point…

Differential Geometry · Mathematics 2024-07-23 Ahmad Reza Haj Saeedi Sadegh , Shiqi Liu , Yiannis Loizides , Jesus Sanchez

Index theory for Lorentzian Dirac operators is a young subject with significant differences to elliptic index theory. It is based on microlocal analysis instead of standard elliptic theory and one of the main features is that a nontrivial…

Differential Geometry · Mathematics 2025-02-17 Christian Baer , Alexander Strohmaier

Let $G$ be a compact connected Lie group, and $M$ a compact Hamiltonian $G$-space, with moment map $J$. For each $G$-equivariant Hermitian vector bundle $E$ over $M$, one has an associated twisted Spin-C Dirac operator, whose equivariant…

dg-ga · Mathematics 2008-02-03 Eckhard Meinrenken

We mathematically show an equality between the index of a Dirac operator on a flat continuum torus and the $\eta$ invariant of a lattice Dirac operator known as the Wilson Dirac operator with a negative mass when the lattice spacing is…

K-Theory and Homology · Mathematics 2025-06-03 Shoto Aoki , Hidenori Fukaya , Mikio Furuta , Shinichiroh Matsuo , Tetsuya Onogi , Satoshi Yamaguchi

We consider a generalized APS boundary problem for a G-invariant Dirac-type operator, which is not of product type near the boundary. We establish a delocalized version (a so-called Kirillov formula) of the equivariant index theorem for…

Differential Geometry · Mathematics 2017-09-20 Maxim Braverman , Gideon Maschler

We give a formulation of a deformation of Dirac operator along orbits of a group action on a possibly non-compact manifold to get an equivariant index and a K-homology cycle representing the index. We apply this framework to non-compact…

Differential Geometry · Mathematics 2021-03-02 Hajime Fujita

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

On complete non-compact manifolds with bounded sectional curvature, we consider a class of self-adjoint Dirac-type operators called Dirac-Schr\"odinger operators. Assuming two Dirac-Schr\"odinger operators coincide at infinity, by previous…

Differential Geometry · Mathematics 2026-04-14 Pengshuai Shi
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