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A third order self-adjoint differential operator with periodic boundary conditions and an one-dimensional perturbation has been considered. For this operator, we first show that the spectrum consists of simple eigenvalues and finitely many…

Classical Analysis and ODEs · Mathematics 2022-12-21 Yixuan Liu , Jun Yan

We consider the Neumann-Poincar'e (double layer potential) operator in 3D elasicity on a smooth closed surface. Its essential spectrum consists of 3 points. We find the asymptotics of sequences of eigenvalues converging to these three…

Analysis of PDEs · Mathematics 2022-12-06 Grigori Rozenblum

We characterize possible spectra of rank-one perturbations B of a self-adjoint operator A with discrete spectrum and, in particular, prove that the spectrum of B may include any number of real or non-real eigenvalues of arbitrary algebraic…

Spectral Theory · Mathematics 2020-06-23 Oles Dobosevych , Rostyslav Hryniv

This paper deals with the generalized spectrum of continuously invertible linear operators defined on infinite dimensional Hilbert spaces. More precisely, we consider two bounded, coercive, and self-adjoint operators $\bc{A, B}: V\mapsto…

Numerical Analysis · Mathematics 2021-03-02 Tomáš Gergelits , Bjørn Fredrik Nielsen , Zdeněk Strakoš

We describe a midi-superspace quantization scheme for generic single horizon black holes in which only the spatial diffeomorphisms are fixed. The remaining Hamiltonian constraint yields an infinite set of decoupled eigenvalue equations: one…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. Gegenberg , G. Kunstatter , R. D. Small

The purpose of this paper is to study spectral properties of non-self-adjoint Schr\"odinger operators $-\Delta-\frac{(n-2)^2}{4|x|^{2}}+V$ on $\mathbb{R}^n$ with complex-valued potentials $V\in L^{p,\infty}$, $p>n/2$. We prove Keller type…

Spectral Theory · Mathematics 2016-08-08 Haruya Mizutani

Eigenvalue problems for semidefinite operators with infinite dimensional kernels appear for instance in electromagnetics. Variational discretizations with edge elements have long been analyzed in terms of a discrete compactness property. As…

Numerical Analysis · Mathematics 2013-06-24 Snorre Harald Christiansen , Ragnar Winther

The ordered eigenvalues define a Lipschitz map on the real vector space of Hermitian $d \times d$ matrices. We prove that this map acts continuously, but not uniformly continuously, by superposition on the Sobolev spaces $W^{1,q}$, for all…

Functional Analysis · Mathematics 2026-03-25 Adam Parusiński , Armin Rainer

Let $A(t)$ be a holomorphic family of self-adjoint operators of type (B) on a complex Hilbert space $\mathcal{H}$. Kato-Rellich perturbation theory says that isolated eigenvalues of $A(t)$ will be analytic functions of $t$ as long as they…

Functional Analysis · Mathematics 2020-07-08 Brian Lins

Spectrum is an important numerical invariant of an isolated hypersurface singularity, connecting its topological and analytic structures. The well-known Hertling conjecture tells the relation of range and variance of exponents i.e. elements…

Algebraic Geometry · Mathematics 2026-02-20 Quan Shi , Yang Wang , Huaiqing Zuo

We qualify the main features of the spectrum of the Hamiltonian of point interaction for a three-dimensional quantum system consisting of three point-like particles, two identical fermions, plus a third particle of different species, with…

Mathematical Physics · Physics 2018-12-05 Simon Becker , Alessandro Michelangeli , Andrea Ottolini

We address the problem of computing the smallest symplectic eigenvalues and the corresponding eigenvectors of symmetric positive-definite matrices in the sense of Williamson's theorem. It is formulated as minimizing a trace cost function…

Optimization and Control · Mathematics 2022-01-06 Nguyen Thanh Son , P. -A. Absil , Bin Gao , Tatjana Stykel

In this paper I give an explicit construction of an analogue of eigenspace for points of the singular spectrum of a self-adjoint operator. This construction is based on an abstract version of homogeneous Lippmann-Schwinger equation.

Spectral Theory · Mathematics 2021-11-22 Nurulla Azamov

An ensemble of 2 x 2 pseudo-Hermitian random matrices is constructed that possesses real eigenvalues with level-spacing distribution exactly as for the Gaussian Unitary Ensemble found by Wigner. By a re-interpretation of Connes' spectral…

Quantum Physics · Physics 2007-05-23 Zafar Ahmed , Sudhir R. Jain

The focus of this paper is on the probability, $E_\beta(0;J)$, that a set $J$ consisting of a finite union of intervals contains no eigenvalues for the finite $N$ Gaussian Orthogonal ($\beta=1$) and Gaussian Symplectic ($\beta=4$) Ensembles…

solv-int · Physics 2014-11-18 Craig A. Tracy , Harold Widom

This paper is devoted to providing quantitative bounds on the location of eigenvalues, both discrete and embedded, of non self-adjoint Lam\'e operators of elasticity $-\Delta^\ast + V$ in terms of suitable norms of the potential $V$. In…

Spectral Theory · Mathematics 2021-01-26 Biagio Cassano , Lucrezia Cossetti , Luca Fanelli

We investigate relations between spectral properties of a single-centre point-interaction Hamiltonian describing a particle confined to a bounded domain $\Omega\subset\mathbb{R}^{d},\: d=2,3$, with Dirichlet boundary, and the geometry of…

Mathematical Physics · Physics 2019-12-10 Pavel Exner , Andrea Mantile

First, we recount a history of how certain methods using natural self-adjoint operators have, thus far, failed to prove the Riemann Hypothesis. In Section 2, we set the analytical context necessary to have genuine proofs in later sections,…

Number Theory · Mathematics 2022-08-04 Adrienne Sands

Let $J,E\subset\mathbb R$ be two multi-intervals with non-intersecting interiors. Consider the following operator $$A:\, L^2( J )\to L^2(E),\ (Af)(x) = \frac 1\pi\int_{ J } \frac {f(y)\text{d} y}{x-y},$$ and let $A^\dagger$ be its adjoint.…

Functional Analysis · Mathematics 2020-08-25 Marco Bertola , Alexander Katsevich , Alexander Tovbis

We consider the complex eigenvalues of the induced spherical Ginibre ensemble with symplectic symmetry and establish the local universality of these point processes along the real axis. We derive scaling limits of all correlation functions…

Probability · Mathematics 2023-05-31 Sung-Soo Byun , Peter J. Forrester