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Perturbation of eigenvalues of the Klein-Gordon operators (1807.11612v3)
Published 31 Jul 2018 in math-ph, math.MP, and math.SP
Abstract: We prove inclusion theorems for both spectra and essential spectra as well as two-sided bounds for isolated eigenvalues for Klein-Gordon type Hamiltonian operators. We first study operators of the form $JG$, where $J$, $G$ are selfadjoint operators on a Hilbert space, $J = J* = J{-1}$ and $G$ is positive definite and then we apply these results to obtain bounds of the Klein-Gordon eigenvalues under the change of the electrostatic potential. The developed general theory allows applications to some other instances, as e.g. the Sturm-Liouville problems with indefinite weight.