Magnetic dipole operator from chiral effective field theory for many-body expansion methods

TL;DR

This paper derives the magnetic dipole operator in basis states for nuclear many-body calculations using chiral effective field theory, enabling improved predictions of nuclear magnetic properties.

Contribution

It provides a detailed derivation of the magnetic dipole operator including two-body contributions from chiral EFT for various basis states used in nuclear many-body methods.

Findings

Benchmark comparisons with quantum Monte Carlo results for three-body systems.

Explicit matrix elements for magnetic dipole operators in different basis states.

Facilitates accurate calculations of nuclear magnetic properties.

Abstract

Many-body approaches for atomic nuclei generally rely on a basis expansion of the nuclear states, interactions, and current operators. In this work, we derive the representation of the magnetic dipole operator in plane-wave and harmonic-oscillator basis states, as needed for Faddeev calculations of few-body systems or many-body calculations within, e.g., the no-core shell model, the in-medium renormalization group, coupled-cluster theory, or the nuclear shell model. We focus in particular on the next-to-leading-order two-body contributions derived from chiral effective field theory. We provide detailed benchmarks and also comparisons with quantum Monte Carlo results for three-body systems. The derived operator matrix elements represent the basic input for studying magnetic properties of atomic nuclei based on chiral effective field theory.