Widths of low-lying nucleon resonances in light nuclei in the source-term approach

This paper presents the first application of the shell-model-based source-term approach (STA) to calculations of widths of neutron and proton resonances for some $0p$-shell nuclei. The STA widths are compared to (i) the popular standard approach that uses the product of shell-model spectroscopic factors and single-particle widths obtained from a potential model with standard potential well geometry, (ii) available predictions from a similar approach with variational Monte Carlo (VMC) wave functions, and (iii) experimental data. It is found out that the STA predictions are often smaller than those made within the widely used standard practice (ii), thus indicating that reduction of spectroscopic strength, known in bound states, persists in the continuum. In most cases the STA gives better agreement with experiment than the standard approach does and is comparable to results obtained from the VMC-based integral equations approach. The agreement of the STA widths with experimental values is of quality similar to that seen in predictions of asymptotic normalization coefficients made in the same approach.