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This paper is devoted to the study of shape optimization problems for the first eigenvalue of the elliptic operator with drift L = --$\Delta$+V (x)\cdot \nabla with Dirichlet boundary conditions, where V is a bounded vector field. In the…

Analysis of PDEs · Mathematics 2019-05-17 Emmanuel Russ , Baptiste Trey , Bozhidar Velichkov

We derive a formula for the essential norm of a composition operator on the minimal Mobius invariant space of analytic functions. As an application, we show that the essential norm of a non-compact composition operator is at least 1. We…

Complex Variables · Mathematics 2010-08-05 Themis Mitsis , Michael Papadimitrakis

We characterize the commutant of the analytic Toeplitz operators modulo operators of Schatten-p-class on suitable multivariable domains. We show that a result of J. Xia on compact perturbations of Toeplitz operators on the unit disc remains…

Functional Analysis · Mathematics 2016-06-28 Michael Didas , Jörg Eschmeier , Dominik Schillo

We deduce various norm equivalences, and convolution estimates for the modulation space $M^{\sharp ,q}_{(\omega )}$ consisting of all $f\in M^{\infty ,q}_{(\omega )}$ such that $|V_\phi f \cdot \omega |$ satisfies a mild vanishing condition…

Functional Analysis · Mathematics 2026-04-14 Elmira Nabizadeh-Morsalfard , Christine Pfeuffer , Nenad Teofanov , Joachim Toft

We revisit the problem of semiclassical spectral asymptotics for a pure magnetic Schr\"odinger operator on a two-dimensional Riemannian manifold. We suppose that the minimal value $b_0$ of the intensity of the magnetic field is strictly…

Spectral Theory · Mathematics 2013-12-20 Bernard Helffer , Yuri A. Kordyukov

We show that tensoring the Laplace and Dolbeault-Dirac operators of a K\"ahler structure (with closed integral) by a negative Hermitian holomorphic module, produces operators with spectral gaps around zero. The proof is based on the…

Quantum Algebra · Mathematics 2022-06-27 Biswarup Das , Réamonn Ó Buachalla , Petr Somberg

This paper considers paired operators in the context of the Lebesgue Hilbert space $L^2$ on the unit circle and its subspace, the Hardy space $H^2$. The kernels of such operators, together with their analytic projections, which are…

Functional Analysis · Mathematics 2025-01-22 M. Cristina Câmara , Jonathan R. Partington

Let $\varphi$ be a function in the Hardy space $H^2(\mathbb{T}^d)$. The associated (small) Hankel operator $\mathbf{H}_\varphi$ is said to have minimal norm if the general lower norm bound $\|\mathbf{H}_\varphi\| \geq…

Functional Analysis · Mathematics 2022-07-29 Ole Fredrik Brevig

In this paper, we establish the asymptotic estimates for the norms of the matrix dilation operators on modulation spaces. As an application, we study the boundedness on modulation spaces of Hausdorff operators. The definition of Hausdorff…

Classical Analysis and ODEs · Mathematics 2022-07-20 Weichao Guo , Jiangkun Luo , Guoping Zhao

We consider discrete Schr\"odinger operators on the half line with potentials generated by the doubling map and continuous sampling functions. We show that the essential spectrum of these operators is always connected. This result is…

Spectral Theory · Mathematics 2023-01-04 David Damanik , Jake Fillman

We obtain the off-diagonal Muckenhoupt-Wheeden conjecture for Calder\'on-Zygmund operators. Namely, given $1<p<q<\infty$ and a pair of weights $(u,v)$, if the Hardy-Littlewood maximal function satisfies the following two weight…

Classical Analysis and ODEs · Mathematics 2018-10-10 David Cruz-Uribe , José María Martell , Carlos Pérez

We define and study Toeplitz operators in the space of Herglotz solutions of the Helmholtz equation in $R^d$. As the most traditional definition of Toeplitz operators via Bergman-type projection is not available here, we use an approach…

Functional Analysis · Mathematics 2016-05-24 Grigori Rozenblum , Nikolai Vasilevski

Boundedness of weighted composition operators $W_{u,\varphi}$ acting on the classical Dirichlet space $\mathcal{D}$ as $W_{u,\varphi}f= u\, (f\circ \varphi)$ is studied in terms of the multiplier space associated to the symbol $\varphi$,…

Functional Analysis · Mathematics 2015-03-05 I. Chalendar , E. A. Gallardo-Gutiérrez , J. R. Partington

We propose a method for the spectral analysis of unbounded operator matrices in a general setting which fully abstains from standard perturbative arguments. Rather than requiring the matrix to act in a Hilbert space $\mathcal{H}$, we extend…

Spectral Theory · Mathematics 2022-05-25 Borbala Gerhat

We present a systematic approach for the semiclassical treatment of many-body dynamics of interacting, open spin systems. Our approach overcomes some of the shortcomings of the recently developed discrete truncated Wigner approximation…

Quantum Physics · Physics 2022-12-01 Christopher D. Mink , David Petrosyan , Michael Fleischhauer

In this paper, we establish the essential criteria for the hyponormality and quasinormality of the unbounded Toeplitz operator $T_{\varphi}$ with non-harmonic symbol, acting on the Fock-Sobolev space $F^{2, m}(\mathbb{C})$. The study shows…

Functional Analysis · Mathematics 2025-12-02 Anuradha Gupta , Kajal Negi

Inversion of Toeplitz matrices with singular symbol. Minimal eigenvalues. Three results are stated in this paper. The first one is devoted to the study of the orthogonal polynomial with respect of the weight $\varphi_{\alpha} (\theta)=\vert…

Functional Analysis · Mathematics 2010-05-25 Philippe Rambour , Abdellatif Seghier

In this paper, we analyze the convergence behavior of Hermite-type sampling Kantorovich operators in the context of mixed norm spaces. We prove certain direct approximation theorems, including the uniform convergence theorem, the…

Functional Analysis · Mathematics 2025-06-04 Puja Sonawane , A. Sathish Kumar

In this paper we prove a two-term asymptotic formula for for the spectral counting function for a 2D magnetic Schr\"odinger operator on a domain (with Dirichlet boundary conditions) in a semiclassical limit and with strong magnetic field.…

Mathematical Physics · Physics 2011-08-04 Horia D. Cornean , Soren Fournais , Rupert Frank , Bernard Helffer

We study minimizers of non-autonomous functionals \begin{align*} \inf_u \int_\Omega \varphi(x,|\nabla u|) \, dx \end{align*} when $\varphi$ has generalized Orlicz growth. We consider the case where the upper growth rate of $\varphi$ is…

Analysis of PDEs · Mathematics 2022-09-27 Petteri Harjulehto , Peter Hästö , Jonne Juusti
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