Candidate Toroidal Electric Dipole Mode in the Spherical Nucleus ^{58}Ni

Phys Rev Lett. 2024 Dec 6;133(23):232502. doi: 10.1103/PhysRevLett.133.232502.

Abstract

Dipole toroidal modes appear in many fields of physics. In nuclei, such a mode was predicted more than 50 years ago, but clear experimental evidence was lacking so far. Using a combination of high-resolution inelastic scattering experiments with photons, electrons, and protons, we identify for the first time candidates for toroidal dipole excitations in the nucleus ^{58}Ni and demonstrate that transverse electron scattering form factors represent a relevant experimental observable to prove their nature.