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When aiming to apply mathematical results of non-commutative geometry to physical problems the question arises how they translate to a context in which only a part of the spectrum is known. In this article we aim to detect when a…

Mathematical Physics · Physics 2020-03-18 Lisa Glaser , Abel Stern

In this article we discuss density of products of biharmonic functions vanishing on an arbitrarily small part of the boundary. We prove that one can use three or more such biharmonic functions to construct a dense subset of smooth symmetric…

Analysis of PDEs · Mathematics 2025-01-22 Divyansh Agrawal , Sombuddha Bhattacharyya , Pranav Kumar

Dirac's equation of the electron will be discussed by using quaternions as the basis of a new formalism which seems to be very well adapted to the problem. The transformation properties of the equations as well as the invariant and…

History and Philosophy of Physics · Physics 2007-05-23 Cornelius Lanczos

A finite non-commutative geometry consists of a fuzzy space together with a Dirac operator satisfying the axioms of a real spectral triple. This paper addreses the question of how to extract information about these geometries from the…

General Relativity and Quantum Cosmology · Physics 2019-09-04 John W. Barrett , Paul Druce , Lisa Glaser

This paper demonstrates the existence of twistless tori and the associated reconnection bifurcations and meandering curves in the planar circular restricted three-body problem. Near the Lagrangian equilibrium $\mathcal{L}_4$ a twistless…

Mathematical Physics · Physics 2015-06-17 Holger R Dullin , Joachim Worthington

We review the construction of the Dirac operator and its properties in Riemannian geometry and show how the asymptotic expansion of the trace of the heat kernel determines the spectral invariants of the Dirac operator and its index. We also…

Mathematical Physics · Physics 2007-05-23 Ivan G. Avramidi

We investigate solutions of the classical Einstein or supergravity equations that solve any set of quantum corrected Einstein equations in which the Einstein tensor plus a multiple of the metric is equated to a symmetric conserved tensor…

High Energy Physics - Theory · Physics 2008-11-26 A. A. Coley , G. W. Gibbons , S. Hervik , C. N. Pope

Motivated by the trilinear functional of differential one-forms, spectral triple and spectral torsion for the Hodge-Dirac operator, we introduce a multilinear functional of differential one-forms for a finitely summable regular spectral…

Differential Geometry · Mathematics 2025-05-30 Jian Wang , Yong Wang , Mingyu Liu

We provide an explicit resolution of the Abreu equation on convex labeled quadrilaterals. This confirms a conjecture of Donaldson in this particular case and implies a complete classification of the explicit toric K\"ahler-Einstein and…

Differential Geometry · Mathematics 2011-12-15 Eveline Legendre

I investigate the general extension of Einstein's gravity by considering the third rank non-metricity tensor and the torsion tensor. The minimal coupling to Dirac fields faces an ambiguity coming from a severe arbitrariness of the…

General Relativity and Quantum Cosmology · Physics 2018-08-07 G. de Berredo-Peixoto

We present a new formulation of Einstein's equations for an axisymmetric spacetime with vanishing twist in vacuum. We propose a fully constrained scheme and use spherical polar coordinates. A general problem for this choice is the…

General Relativity and Quantum Cosmology · Physics 2015-05-15 Christian Schell , Oliver Rinne

We generalize and simplify an earlier approach. In three dimensions we present the most general averaging formula in lowest order which respects the requirements of covariance. It involves a bitensor, made up of a basis of six tensors, and…

General Relativity and Quantum Cosmology · Physics 2009-07-16 Dieter Gromes

We first review asymptotic twistor theory with its real subspace of null asymptotic twistors. This is followed by a description of an asymptotic version of the Kerr theorem that produces regular asymptotically shear free null geodesic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Ezra T. Newman

We compute all 2-covariant tensors naturally constructed from a semiriemannian metric which are divergence-free and have weight greater than -2. As a consequence, it follows a characterization of the Einstein tensor as the only, up to a…

General Relativity and Quantum Cosmology · Physics 2009-05-27 Jose Navarro , Juan B. Sancho

In this paper, we introduce the spectral Einstein functional for perturbations of Dirac operators on manifolds with boundary. Furthermore, we provide the proof of the Dabrowski-Sitarz-Zalecki type theorems associated with the spectral…

Geometric Topology · Mathematics 2023-12-06 Sining Wei , Yong Wang

We consider a generic curved non-commutative torus extending the notion of conformally deformed non-commutative torus from \cite{Connes-Tretkoff}. In general, a curved non-commutative torus is no longer represented by a spectral triple, not…

Operator Algebras · Mathematics 2019-10-03 Fedor Sukochev , Dmitriy Zanin

In this paper, we define the spectral Einstein functional associated with the Dirac operator for manifolds with boundary. And we give the proof of Kastler-Kalau-Walze type theorem for the spectral Einstein functional associated with the…

Differential Geometry · Mathematics 2022-12-26 Tong Wu , Yong Wang

We describe how the presence of the antisymmetric tensor (torsion) on the world sheet action of string theory renders the size of the target space a gauge non invariant quantity. This generalizes the R <--> 1/R symmetry in which momenta and…

High Energy Physics - Theory · Physics 2009-10-31 Fedele Lizzi

Inspired by a similar analysis for the vacuum conformal Einstein field equations by Paetz [Ann. H. Poincar\'e 16, 2059 (2015)], in this article we show how to construct a system of quasilinear wave equations for the geometric fields…

General Relativity and Quantum Cosmology · Physics 2019-07-16 Diego A. Carranza , Adem E. Hursit , Juan A. Valiente Kroon

The Dirac equation is solved to obtain its approximate bound states for a spin-1/2 particle in the presence of trigonometric Poschl-Teller (tPT) potential including a Coulomb-like tensor interaction with arbitrary spin-orbit quantum number…

Quantum Physics · Physics 2013-08-02 Babatunde J. Falaye , Sameer M. Ikhdair