2014/06/09 by Saori Pastore, S. Pastore, R. B. Wiringa +2 · 1 citation
Physics and Astronomy · #Advanced Chemical Physics Studies #Atomic and Molecular Physics #Nuclear physics research studies #nucl-th
paper · pdf · doi:10.1103/physrevc.90.024321
13 pages, 6 figures
arxiv created 2014/06/09 · openalex publication_date 2014/08/25 · arxiv updated 2015/06/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We report quantum Monte Carlo calculations of electromagnetic transitions in 8Be. The realistic Argonne v18 two-nucleon and Illinois-7 three-nucleon potentials are used to generate the ground state and nine excited states, with energies that are in excellent agreement with experiment. A dozen M1 and eight E2 transition matrix elements between these states are then evaluated. The E2 matrix elements are computed only in impulse approximation, with those transitions from broad resonant states requiring special treatment. The M1 matrix elements include two-body meson-exchange currents derived from chiral effective field theory, which typically contribute 20%--30% of the total expectation value. Many of the transitions are between isospin-mixed states; the calculations are performed for isospin-pure states and then combined with empirical mixing coefficients to compare to experiment. Alternate mixings are also explored. In general, we find that transitions between states that have the same dominant spatial symmetry are in reasonable agreement with experiments, but transitions between different spatial symmetries are often underpredicted.