Quantum Brownian motion. II

This paper is devoted to generalize some previous results presented in Gaioli et al., Int. J. Theor. Phys. 36, 2167 (1997). We evaluate the autocorrelation function of the stochastic acceleration and study the asymptotic evolution of the mean occupation number of a harmonic oscillator playing the role of a Brownian particle. We also analyze some deviations from the Bose population at low temperatures and compare it with the deviations from the exponential decay law of an unstable quantum system.