Renormalized Spectrum of Three-Level Localized Quasiparticle Interacting with Polarization Phonons at Cryogenic Temperature

摘要： Based on the generalized method of Feynman–Pines diagram technique, a new method of calculation of the mass operator in the Fourier image of Green’s function is proposed for the system of a three-level localized quasiparticle interacting with polarization phonons at T = 0 K. The revealed main class of diagrams gives the opportunity to write the renormalized mass operator in a form of continuous branch chain fraction with typical links. Such presentation allows effective accounting of multi-phonon processes. It is shown that the renormalized energy spectrum contains the complexes of bound-to-phonon states of the quasiparticle. These complexes essentially differ for the resonant and non-resonant systems.