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We show the contractibility of spaces of invariant Riemannian metrics of positive scalar curvature on compact connected manifolds of dimension at least two, with and without boundary and equipped with compact Lie group actions. On manifolds…

Differential Geometry · Mathematics 2025-06-23 Christian Baer , Bernhard Hanke

Let M be a compact manifold with a spin structure \chi and a Riemannian metric g. Let \lambda_g^2 be the smallest eigenvalue of the square of the Dirac operator with respect to g and \chi. The \tau-invariant is defined as \tau(M,\chi):= sup…

Differential Geometry · Mathematics 2015-06-26 Bernd Ammann , Emmanuel Humbert

In this work, optimal rigidity results for eigenvalues on K\"ahler manifolds with positive Ricci lower bound are established. More precisely, for those K\"ahler manifolds whose first eigenvalue agrees with the Ricci lower bound, we show…

Differential Geometry · Mathematics 2024-12-24 Jianchun Chu , Feng Wang , Kewei Zhang

We use certain Morse functions to construct conformal metrics such that the eigenvalue vector of modified Schouten tensor belongs to a given cone. As a result, we prove that any Riemannian metric on compact 3-manifolds with boundary is…

Differential Geometry · Mathematics 2023-08-14 Rirong Yuan

We derive a formula for the index of a Dirac operator on a compact, even-dimensional incomplete edge space satisfying a "geometric Witt condition". We accomplish this by cutting off to a smooth manifold with boundary, applying the…

Differential Geometry · Mathematics 2016-09-09 Pierre Albin , Jesse Gell-Redman

We obtain sharp lower bounds for the first eigenvalue of four types of eigenvalue problem defined by the bi-Laplace operator on compact manifolds with boundary and determine all the eigenvalues and the corresponding eigenfunctions of a…

Analysis of PDEs · Mathematics 2020-01-22 Qiaoling Wang , Changyu Xia

It has been recently shown that the eigenvalues of the Dirac operator can be considered as dynamical variables of Euclidean gravity. The purpose of this paper is to explore the possiblity that the eigenvalues of the Dirac operator might…

General Relativity and Quantum Cosmology · Physics 2009-10-30 I. V. Vancea

In this paper, we investigate critical points of the Laplacian's eigenvalues considered as functionals on the space of Riemmannian metrics or a conformal class of metrics on a compact manifold. We obtain necessary and sufficient conditions…

Metric Geometry · Mathematics 2009-11-13 Ahmad El Soufi , Said Ilias

The main result of this article is a Llarull-type rigidity statement for scalar curvature on Riemannian spin manifolds with cone-like singularities in odd dimensions. The even dimensional analog was proven in an earlier work together with…

Differential Geometry · Mathematics 2026-05-04 Lukas Schoenlinner

Under various elliptic boundary conditions, we obtain lower eigenvalue estimates for Dirac operators by using Hormander's weighted $L^2$-technique. Lower bounds in terms of the volume of the underlying manifolds are also deduced from the…

Differential Geometry · Mathematics 2019-07-16 Qingchun Ji , Li Lin

We consider the problem of preserving weighted Riemannian metrics of positive Bakry-\'Emery Ricci curvature along surgery. We establish two theorems of this type: One for connected sums, and one for surgeries along higher-dimensional…

Differential Geometry · Mathematics 2024-11-27 Philipp Reiser , Francesca Tripaldi

In this paper we study spaces of Riemannian metrics with lower bounds on intermediate curvatures. We show that the spaces of metrics of positive p-curvature and k-positive Ricci curvature on a given high-dimensional Spin-manifold have many…

Differential Geometry · Mathematics 2022-01-28 Georg Frenck , Jan-Bernhard Kordaß

By using the Ljusternik-Schnirelman principle, we establish the existence of a nondecreasing sequence of nonnegative eigenvalues for the p-Dirac operator on compact spin manifold. Using the biorthogonal system theory on separable Banach…

Analysis of PDEs · Mathematics 2023-06-28 Lei Xian , Xu Yang

The so-called Dirac oscillator was proposed as a modification of the free Dirac equation which reproduces many of the properties of the simple harmonic oscillator but accompanied by a strong spin-orbit coupling term. It has yet to be…

Quantum Physics · Physics 2014-09-19 C. R. Hagen

We compare the eigenvalues of the Dirac and Laplace operator on a two-dimensional torus with respect to the trivial spin structure. In particular, we compute their variation up to order 4 upon deformation of the flat metric, study the…

Differential Geometry · Mathematics 2007-05-23 Ilka Agricola , Bernd Ammann , Thomas Friedrich

Let $e_\l(x)$ be an eigenfunction with respect to the Dirichlet Laplacian $\Delta_N$ on a compact Riemannian manifold $N$ with boundary: $\Delta_N e_\l=\l^2 e_\l$ in the interior of $N$ and $e_\l=0$ on the boundary of $N$. We show the…

Analysis of PDEs · Mathematics 2010-02-04 Yiqian Shi , Bin Xu

Let (M, g) be a compact Einstein Riemannian manifold with boundary. We show that under certain conditions, the map that associates to a metric on M its Ricci curvature, its induced conformal class on the boundary, and its mean curvature on…

Differential Geometry · Mathematics 2025-03-25 Erwann Delay

We find a unique torsion free Riemannian spin connection for the natural Killing metric on the quantum group $C_q[SL_2]$, using a recent frame bundle formulation. We find that its covariant Ricci curvature is essentially proportional to the…

Quantum Algebra · Mathematics 2007-05-23 Shahn Majid

For Dirac operators, which have discrete spectra, the concept of eigenvalues gradient is given and formulae for this gradients are obtained in terms of normalized eigenfunctions. It is shown how the gradient is being used to describe…

Classical Analysis and ODEs · Mathematics 2017-05-08 Tigran Harutyunyan , Yuri Ashrafyan

We show that any Riemannian metric conformal to the round metric on $S^n$, for $n\geq 4$, arises as a limit of a sequence of Riemannian metrics of positive scalar curvature on $S^n$ in the sense of uniform convergence of Riemannian…

Differential Geometry · Mathematics 2024-11-19 Man-Chun Lee , Peter M. Topping