THRESHOLD EIGENVALUES AND RESONANCES OF A FRIEDRICHS MODEL WITH RANK TWO PERTURBATION
In this paper in the Hilbert space a bounded self-adjoint Friedrichs model with rank two perturbation is considered. Number and location of the eigenvalues of are studied. An existence conditions of these eigenvalues are found. Under some conditions we prove that the lower (upper) bound of the essential spectrum of is either threshold eigenvalue or virtual level of .