Thermalization in one- plus two-body ensembles for dense interacting boson systems

Employing one- plus two-body random matrix ensembles for bosons, temperature and entropy are calculated, using different definitions, as a function of the two-body interaction strength lambda for a system with 10 bosons (m = 10) in five single-particle levels (N = 5). It is found that in a region lambda similar to lambda(t) At, different definitions give essentially the same values for temperature and entropy, thus defining a thermalization region. Also, (m, N) dependence of lambda(t) has been derived. It is seen that lambda(t) is much larger than the lambda values where level fluctuations change from Poisson to GOE and strength functions change from Breit-Wigner to Gaussian. (C) 2012 Elsevier B.V. All rights reserved.