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This paper studies geometric structures on noncommutative hypersurfaces within a module-theoretic approach to noncommutative Riemannian (spin) geometry. A construction to induce differential, Riemannian and spinorial structures from a…

Quantum Algebra · Mathematics 2020-09-21 Hans Nguyen , Alexander Schenkel

It is well-known that any covering space of a Riemannian manifold has the natural structure of a Riemannian manifold. This article contains a noncommutative generalization of this fact. Since any Riemannian manifold with a Spin-structure…

Operator Algebras · Mathematics 2018-04-18 Petr Ivankov

In this article, we prove that on any compact spin manifold of dimension m congruent 0,6,7 mod 8, there exists a metric, for which the associated Dirac operator has at least one eigenvalue of multiplicity at least two. We prove this by…

Differential Geometry · Mathematics 2016-11-08 Nikolai Nowaczyk

We show that for generic Riemannian metrics on a simply-connected closed spin manifold of dimension at least 5 the dimension of the space of harmonic spinors is no larger than it must be by the index theorem. The same result holds for…

Differential Geometry · Mathematics 2011-07-22 Christian Baer , Mattias Dahl

Let $(M_i, g_i)_{i \in \mathbb{N}}$ be a sequence of spin manifolds with uniform bounded curvature and diameter that converges to a lower dimensional Riemannian manifold $(B,h)$ in the Gromov-Hausdorff topology. Lott showed that the…

Spectral Theory · Mathematics 2019-05-08 Saskia Roos

We prove here that given a proper isometric action $K\times M\to M$ on a complete Riemannian manifold $M$ then every continuous isometric flow on the orbit space $M/K$ is smooth, i.e., it is the projection of an $K$-equivariant smooth flow…

Differential Geometry · Mathematics 2014-05-14 Marcos M. Alexandrino , Marco Radeschi

We give results about the L^2 kernel and the spectrum of the Dirac operator on a complete Riemannian manifold which is conformally equivalent to the interior of a Riemannian manifold with nonempty boundary.

Differential Geometry · Mathematics 2007-05-23 John Lott

Let $M$ be an orientable compact flat Riemannian manifold endowed with a spin structure. In this paper we determine the spectrum of Dirac operators acting on smooth sections of twisted spinor bundles of $M$, and we derive a formula for the…

Differential Geometry · Mathematics 2007-05-23 Roberto Miatello , Ricardo Podesta

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

This is a survey article on a known generalization of Dirac-type operators to transverse operators called basic Dirac operators on Riemannian foliations, which are smooth foliations that have a transverse geometric structure. Construction…

Differential Geometry · Mathematics 2009-09-01 Ken Richardson

Odd-dimensional Riemannian spaces that are non-orientable, but have a pin structure, require the consideration of the twisted adjoint representation of the corresponding pin group. It is shown here how the Dirac operator should be modified,…

High Energy Physics - Theory · Physics 2011-04-15 Andrzej Trautman

Compatibility of symmetric quantization of the Dirac equation in a curved space with general covariance gives a special representation of the spin connections in which their dot product with the Dirac gamma matrices becomes equal to the…

Quantum Physics · Physics 2017-10-03 A. D. Alhaidari

Is is known that the loop space associated to a Riemannian manifold admits a quasi-symplectic structure. This article shows that this structure is not likely to recover the underlying Riemannian metric by proving a result that is a strong…

Symplectic Geometry · Mathematics 2010-09-16 Vicente Munoz , Francisco Presas

For any manifold M, the direct sum TM \oplus T*M carries a natural inner product given by the pairing of vectors and covectors. Differential forms on M may be viewed as spinors for the corresponding Clifford bundle, and in particular there…

Differential Geometry · Mathematics 2011-10-10 Anton Alekseev , Henrique Bursztyn , Eckhard Meinrenken

We describe the shape of the symplectic Dirac operators on Hermitian symmetric spaces. For this, we consider these operators as families of operators that can be handled more easily than the original ones.

Symplectic Geometry · Mathematics 2008-04-24 Steffen Brasch , Katharina Habermann , Lutz Habermann

In this note, we look at estimates for the scalar curvature k of a Riemannian manifold M which are related to spin^c Dirac operators: We show that one may not enlarge a Kaehler metric with positive Ricci curvature without making k smaller…

Differential Geometry · Mathematics 2008-09-16 S. Goette , U. Semmelmann

By a theorem of Mclean, the deformation space of an associative submanifold Y of an integrable G_2 manifold (M,\phi) can be identified with the kernel of a Dirac operator D:\Omega^{0}(\nu) -->\Omega^{0}(\nu) on the normal bundle \nu of Y.…

Geometric Topology · Mathematics 2007-08-20 Selman Akbulut , Sema Salur

The issue of general covariance of spinors and related objects is reconsidered. Given an oriented manifold $M$, to each spin structure $\sigma$ and Riemannian metric $g$ there is associated a space $S_{\sigma, g}$ of spinor fields on $M$…

Mathematical Physics · Physics 2012-12-06 Ludwik Dabrowski , Giacomo Dossena

We present a new description of the spectrum of the (spin-) Dirac operator $D$ on lens spaces. Viewing a spin lens space $L$ as a locally symmetric space $\Gamma\backslash \operatorname{Spin}(2m)/\operatorname{Spin}(2m-1)$ and exploiting…

Differential Geometry · Mathematics 2017-06-30 Sebastian Boldt , Emilio A. Lauret

In this article, we prove a Sobolev-like inequality for the Dirac operator on closed compact Riemannian spin manifolds with a nearly optimal Sobolev constant. As an application, we give a criterion for the existence of solutions to a…

Differential Geometry · Mathematics 2009-03-10 Simon Raulot