  For many-body Fermi systems we determine the dependence of the Breit-Wigner
width and inverse participation ratio (IPR) on interaction strength U > Uc and
energy excitation dE > dE_ch when a crossover from Poisson to Wigner-Dyson
P(s)-statistics takes place. At U > Uc the eigenstates are composed of a large
number of noninteracting states and even for U < Uc there is a regime where
P(s) is close to the Poisson distribution but IPR >> 1.

Condensed Matter