Isospin-Conservation Violation in Two-Nucleon Transfer Reactions

The analog ($p$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) and ($p, t$) reactions on ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been studied by a second-order distorted-wave Born-approximation (DWBA) theory. Nucleon transfer is assumed to occur here only one nucleon at a time. The contribution of the isospin-1 intermediate-state projectile was made small at forward angles by increasing the imaginary part of the corresponding optical potential. This increase can be associated with the preferential decay of an isospin-1 projectile. Convergence of the DWBA is studied by comparing one- and two-step calculations.