Using Pairing to Improve Spherical QRPA Calculations of Low-Lying Octupole Excitations

Octupole deformation, though less common than quadrupole deformation, plays a crucial role in low-energy nuclear structure and symmetry-violating observables. We investigate low-lying octupole collectivity using spherical HF-BCS QRPA with Skyrme interactions. For nuclei exhibiting strong octupole correlations, we show that increasing the pairing strength improves QRPA results, even under the constraint of spherical symmetry. We demonstrate this effect using Gd isotopes as representative examples. These findings highlight the need to revisit common assumptions in QRPA applications. Counterintuitively, forcing spherical QRPA solutions with increased pairing can lead to more accurate predictions of low-lying octupole strength.