2009/08/17 by A. C. Hayes, A. A. Kwiatkowski
Physics and Astronomy · #Atomic and Molecular Physics #Nuclear physics research studies #Quantum Chromodynamics and Particle Interactions #nucl-th
paper · pdf · doi:10.1103/physrevc.81.054301
published as Phys.Rev.C81:054301,2010 · Calculations extended to 14hw (previous version only went up to 10hw)
arxiv created 2009/08/17 · openalex publication_date 2010/05/07 · arxiv updated 2010/05/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We study the structure of the no-core shell model wave functions for 6Li and 12C by investigating the ground state and first excited state electron scattering charge form factors. In both nuclei, large particle-hole (ph) amplitudes in the wave functions appear with the opposite sign to that needed to reproduce the shape of the (e,e^\ensuremath') form factors, the charge radii, and the B(E2) values for the lowest two states. The difference in sign appears to arise mainly from the monopole \ensuremathΔ\ensuremathℏ\ensuremathω=2 matrix elements of the kinetic and potential energy (T+V) that transform under the harmonic oscillator SU(3) symmetries as (\ensuremathλ,\ensuremathμ)=(2,0). These are difficult to determine self-consistently, but they have a strong effect on the structure of the low-lying states and on the giant monopole and quadrupole resonances. The Lee-Suzuki transformation, used to account for the restricted nature of the space in terms of an effective interaction, introduces large higher-order \ensuremathΔ\ensuremathℏ\ensuremathω=n,n>2, ph amplitudes in the wave functions. The latter ph excitations aggravate the disagreement between the experimental and predicted (e,e^\ensuremath') form factors with increasing model spaces, especially at high momentum transfers. For sufficiently large model spaces, the situation begins to resolve itself for 6Li, but the convergence is slow. A prescription to constrain the ph excitations would likely accelerate convergence of the calculations.