17 citations · 29 across the 10 of their papers we have counts for
12 papers
Sharp spectral bounds for complex perturbations of the indefinite Laplacian
Jean-Claude Cuenin, Orif O. Ibrogimov
We derive quantitative bounds for eigenvalues of complex perturbations of the indefinite Laplacian on the real line. Our results substantially improve existing results even for rea…
Location of eigenvalues of non-self-adjoint discrete Dirac operators
Biagio Cassano, Orif O. Ibrogimov, David Krejcirik +1
We provide quantitative estimates on the location of eigenvalues of one-dimensional discrete Dirac operators with complex -potentials for . As a corollar…
Spectral enclosures for non-self-adjoint discrete Schrödinger operators
Orif O. Ibrogimov, František Štampach
We study location of eigenvalues of one-dimensional discrete Schrödinger operators with complex -potentials for . In the case of -potentials…
Discrete eigenvalues of the spin-boson Hamiltonian with two photons: on a problem of Minlos and Spohn
Orif O. Ibrogimov
Under minimal regularity conditions on the photon dispersion and the coupling function, we prove that the spin-boson model with two massless photons in cannot have m…
Spectral analysis of the spin-boson Hamiltonian with two bosons for arbitrary coupling and bounded dispersion relation
Orif O. Ibrogimov
We study the spectrum of the spin-boson Hamiltonian with two bosons for arbitrary coupling in the case when the dispersion relation of the free field is a bounded function. W…
Spectral analysis of the spin-boson Hamiltonian with two photons for arbitrary coupling
Orif O. Ibrogimov
We study the spectrum of the spin-boson model with two photons in for arbitrary coupling . It is shown that the discrete spectrum is finite and the essential sp…
Essential spectrum of elliptic systems of pseudo-differential operators on
Orif O. Ibrogimov, Christiane Tretter
Inspired by a result of Wong (Commun. Partial Differ. Equ. 13(10):1209-1221, 1988), we establish an analytic description of the essential spectrum of non-self-adjoint mixed-order s…
On the spectrum of an operator in truncated Fock space
Orif O. Ibrogimov, Christiane Tretter
We study the spectrum of an operator matrix arising in the spectral analysis of the energy operator of the spin-boson model of radioactive decay with two bosons on the torus. An an…
Essential spectrum of non-self-adjoint singular matrix differential operators
Orif O. Ibrogimov
The purpose of this paper is to study the essential spectrum of non-self-adjoint singular matrix differential operators in the Hilbert space …
Analysis of the essential spectrum of singular matrix differential operators
Orif O. Ibrogimov, Petr Siegl, Christiane Tretter
A complete analysis of the essential spectrum of matrix-differential operators of the form \begin{align} \begin{pmatrix} -\displaystyle{\frac{\rm d}{\rm d t}} p \displ…
Functional Equations and the Cauchy Mean Value Theorem
Zoltan M. Balogh, Orif O. Ibrogimov, Boris S. Mityagin
The aim of this note is to characterize all pairs of sufficiently smooth functions for which the mean value in the Cauchy Mean Value Theorem is taken at a point which has a well-de…
Essential spectrum of systems of singular differential equations
Orif O. Ibrogimov, Heinz Langer, Matthias Langer +1
In this paper we develop a new method to determine the essential spectrum of coupled systems of singular differential equations. Applications to problems from magnetohydrodynamics…