J KUPSCH

Fachbereich Physik, Universitäat Kaiserslautern, D-67653 Kaiserslautern, Germany

Abstract. The dynamics of a particle which is linearly coupled to a boson field is investigated. The boson field induces superselection rules for the momentum of the particle, if the field is infrared divergent. Thereby the Hamiltonian of the total system remains bounded from below.

Keywords. Quantum mechanics; decoherence; infrared divergence.

PACS Nos 03.65.Bz; 11.10.-z