Microscopic Structure of Fundamental Excitations inN=ZNuclei

An extended mean-field model is presented that describes states of different isospin in odd-odd and even-even nuclei. Excitation energies of the $T=1\mathrm{}$ states in even-even as well as $T=0\mathrm{}$ and $T=1\mathrm{}$ states in odd-odd $N=Z$ nuclei are calculated. It is shown that the structure of these states can be determined in a consistent manner when both isoscalar and isovector pairing collectivity as well as isospin projection (treated here within the isocranking approximation) are taken into account. In particular, in odd-odd $N=Z$ nuclei, the interplay between quasiparticle excitations (relevant for the case of $T=0\mathrm{}$ states) and isorotations (relevant for the case of $T=1\mathrm{}$ states) explains the near degeneracy of these states.