MEC

[paper] Up to N3LO heavy-baryon chiral perturbation theory calculation for the M1 properties of three-nucleon systems

Up to N3LO heavy-baryon chiral perturbation theory calculation for the M1 properties of three-nucleon systems

Y.-H. Song et al.

10.1103/PhysRevC.79.064002

M1 properties, comprising magnetic moments and radiative capture of thermal neutron observables, are studied in two- and three-nucleon systems. We use meson exchange current derived up to N3LO using heavy baryon chiral perturbation theory à la Weinberg. Calculations have been performed for several qualitatively different realistic nuclear Hamiltonians, which permits us to analyze model dependence of our results. Our results are found to be strongly correlated with the effective range parameters such as binding energies and the scattering lengths. Taking into account such correlations, the results are in good agreement with the experimental data with small model dependence.

[paper] Quantum Monte Carlo calculations of magnetic moments and M1 transitions in A≤7 nuclei including meson-exchange currents

Quantum Monte Carlo calculations of magnetic moments and M1 transitions in A≤7 nuclei including meson-exchange currents

L.E. Marcucci et al.

doi: 10.1103/PhysRevC.78.065501

Green’s function Monte Carlo calculations of magnetic moments and M1 transitions including two-body meson-exchange current (MEC) contributions are reported for A≤7 nuclei. The realistic Argonne v18 two-nucleon and Illinois-2 three-nucleon potentials are used to generate the nuclear wave functions. The two-body meson-exchange operators are constructed to satisfy the continuity equation with the Argonne v18 potential. The MEC contributions increase the A=3,7 isovector magnetic moments by 16% and the A=6,7 M1 transition rates by 17–34%, bringing them into very good agreement with the experimental data.