ON A MODEL FOR QUANTUM FRICTION .1. FERMIS GOLDEN-RULE AND DYNAMICS AT ZERO-TEMPERATURE

We investigate the dynamics of a quantum particle in a confining poten tial linearly coupled to a bosonic field at temperature zero. For a ma ssive field we show, by employing complex deformation techniques, that Markovian semigroup which approximates the particles dynamics on the time scale tau = lambda(2) t (lambda strength of the coupling) is dete rmined by the resonances of the full energy operator. We also show tha t Markovian master equation technique leads to the right prediction fo r the life-time of resonances. We discuss the dissipation of the parti cle into its ground state both in the time mean and on the above time scale.