On the Spectrum of a Model Operator in Fock Space
arXiv:0805.1284
Abstract
A model operator associated to a system describing four particles in interaction, without conservation of the number of particles, is considered. We describe the essential spectrum of by the spectrum of the channel operators and prove the Hunziker-van Winter-Zhislin (HWZ) theorem for the operator We also give some variational principles for boundaries of the essential spectrum and interior eigenvalues.