BREIT-WIGNER WIDTH AND INVERSE PARTICIPATION RATIO IN FINITE INTERACTING FERMI SYSTEMS

For many-body Fermi systems we determine the dependence of the Breit-W igner width Gamma and inverse participation ratio xi on interaction st rength U greater than or equal to U-c and energy excitation delta E gr eater than or equal to delta E-ch when a crossover from Poisson to Wig ner-Dyson P(s) statistics takes place. At U greater than or equal to U , the eigenstates are composed of a large number of noninteracting sta tes and even for U < U-c there is a regime where P(s)is close to the P oisson distribution but xi much greater than 1.