Spin- and Parity-Resolved Level Densities from the Fine Structure of Giant Resonances

Level densities of J^π=2⁺ and 2^- states extracted from high-resolution studies of $E2$ and $M2$ giant resonances in ⁵⁸Ni and ⁹⁰Zr are used to test recent predictions of a possible parity dependence. The experimental results are compared to a combinatorial approach based on the Hartree-Fock-Bogoliubov model and to shell-model Monte Carlo calculations including both spin and parity projection. No parity dependence is observed experimentally, which is in agreement for ⁹⁰Zr but in contrast with the model predictions for ⁵⁸Ni.