Breit-Wigner to Gaussian transition in strength functions

TL;DR

This paper investigates the transition of strength functions from Breit-Wigner to Gaussian distributions in fermionic systems modeled by embedded Gaussian orthogonal ensembles, revealing a clear transition in the chaotic regime.

Contribution

It demonstrates the Breit-Wigner to Gaussian transition in strength functions using EGOE(2) models, extending previous findings to new fermionic systems.

Findings

Clear transition observed in numerical simulations

Transition occurs in the chaotic domain

Results align with earlier nuclear shell model studies

Abstract

Employing hamiltonians defined by two-body embedded Gaussian orthogonal ensemble of random matrices(EGOE(2)) plus a mean-field producing one-body part, strength functions (for states defined by the one-body part) are constructed for various values of the strength of the chaos generating two-body part. Numerical calculations for six and seven fermion systems clearly demonstrate Breit-Wigner to Gaussian transition, in the chaotic domain, in strength functions as found earlier in nuclear shell model and Lipkin-Meshkov-Glick model calculations.