Transition from isolated to overlapping resonances in the open system of interacting fermions

Abstract

We study the statistical properties of resonance widths and spacings in an open system of interacting fermions at the transition between isolated and overlapping resonances, where a radical change in the width distribution occurs. Our main interest is to reveal how this transition is influenced by the onset of chaos in the internal dynamics as the strength of random two-body interaction between the particles increases. We have found that in the region of overlapped resonances, the fluctuations of the widths (rather than their mean values) are strongly affected by the onset of an internal chaos. The results may be applied to the analysis of neutron cross sections, as well as in the physics of mesoscopic devices with strongly interacting electrons.