Distribution of Resonance Widths and Dynamics of Continuum Coupling

TL;DR

This paper investigates how resonance width distributions in many-body Fermi systems change with continuum coupling strength and intrinsic dynamics, revealing deviations from standard models and connections to super-radiance phenomena.

Contribution

It provides a detailed analysis of how continuum coupling and intrinsic dynamics influence resonance width distributions, highlighting deviations from Porter-Thomas distribution and the super-radiance phase transition.

Findings

Deviations from Porter-Thomas distribution with increased continuum coupling.

Dependence of width distribution on intrinsic chaotic or regular dynamics.

Identification of super-radiance phase transition in the system.

Abstract

We analyze the statistics of resonance widths in a many-body Fermi system with open decay channels. Depending on the strength of continuum coupling, such a system reveals growing deviations from the standard chi-square (Porter-Thomas) width distribution. The deviations emerge from the process of increasing interaction of intrinsic states through common decay channels; in the limit of perfect coupling this process leads to the super-radiance phase transition. The width distribution depends also on the intrinsic dynamics (chaotic vs regular). The results presented here are important for understanding the recent experimental data concerning the width distribution for neutron resonances in nuclei.