Beyond Mean-Field Calculations for Odd-A Nuclei

TL;DR

This paper extends beyond mean-field methods to accurately describe odd-A nuclei using self-consistently blocked HFB states, achieving good agreement with experimental data for 25Mg.

Contribution

First implementation of a beyond mean-field approach for odd-A nuclei using self-consistent blocked HFB states with the same Skyrme interaction in all channels.

Findings

Accurate spectrum reproduction for 25Mg

Agreement with experimental electromagnetic moments and transition strengths

Method applicable to odd-A nuclei across the nuclear chart

Abstract

Beyond mean-field methods are very successful tools for the description of large-amplitude collective motion for even-even atomic nuclei. The state-of-the-art framework of these methods consists in a Generator Coordinate Method based on angular-momentum and particle-number projected triaxially deformed Hatree-Fock-Bogoliubov (HFB) states. The extension of this scheme to odd-mass nuclei is a long-standing challenge. We present for the first time such an extension, where the Generator Coordinate space is built from self-consistently blocked one-quasiparticle HFB states. One of the key points for this success is that the same Skyrme interaction is used for the mean-field and the pairing channels, thus avoiding problems related to the violation of the Pauli principle. An application to 25Mg illustrates the power of our method, as agreement with experiment is obtained for the spectrum, electromagnetic moments, and transition strengths, for both positive and negative parity states and without the necessity for effective charges or effective moments. Although the effective interaction still requires improvement, our study opens the way to systematically describe odd-A nuclei throughout the nuclear chart.