Moments Method for Shell-Model Level Density

TL;DR

This paper presents an advanced Moments Method for calculating nuclear shell-model level densities, accurately matching full diagonalization results and accounting for correlations beyond mean-field approaches.

Contribution

It introduces a refined Moments Method that precisely computes level densities with spin and parity considerations, including the subtraction of spurious center-of-mass excitations.

Findings

Level densities match full diagonalization results when feasible.

The method accounts for correlations, differing from mean-field combinatorics.

Provides pure level density for specific spin and parity states.

Abstract

The modern form of the Moments Method applied to the calculation of the nuclear shell-model level density is explained and examples of the method at work are given. The calculated level density practically exactly coincides with the result of full diagonalization when the latter is feasible. The method provides the pure level density for given spin and parity with spurious center-of-mass excitations subtracted. The presence and interplay of all correlations leads to the results different from those obtained by the mean-field combinatorics.