Quantum Monte Carlo calculations of magnetic moments and M1 transitions in $A \le 9$ nuclei

TL;DR

This paper uses Quantum Monte Carlo methods with chiral effective field theory currents to accurately calculate magnetic moments and M1 transitions in light nuclei, emphasizing the importance of two-body contributions.

Contribution

It introduces a comprehensive approach combining realistic nuclear interactions with chiral EFT currents, including unknown constants fixed by experimental data, to improve magnetic property predictions.

Findings

Two-body currents significantly improve agreement with experimental magnetic moments.

The methodology accurately reproduces M1 transition data for nuclei with A ≤ 9.

Inclusion of two-body effects is crucial for theoretical-experimental consistency.

Abstract

We present Quantum Monte Carlo calculations of magnetic moments and M1 transitions in $A\le 9$ nuclei which take into account contributions of two-body electromagnetic currents. The Hamiltonian utilized to generate the nuclear wave functions includes the realistic Argonne-{\it v}$_{18}$ two-nucleon and the Illinois-7 three-nucleon interactions. The nuclear two-body electromagnetic currents are derived from a pionful chiral effective field theory including up to one-loop corrections. These currents involve unknown Low Energy Constants which have been fixed so as to reproduce a number of experimental data for the two- and three-nucleon systems, such as $np$ phase shifts and deuteron, triton, and $^3$He magnetic moments. This preliminary study shows that two-body contributions provide significant corrections which are crucial to bring the theory in agreement with the experimental data in both magnetic moments and M1 transitions.