Microscopic description of nuclear collective states by symmetry conserving mean field theory

Symmetry conserving mean field theory plays an important role in the microscopic understanding of nuclear collective motion. Several examples are discussed: I) The cranking model is used for the description of the alignment pattern in Actinide nuclei and for an investigation of the giant dipole resonance at large angular velocities and finite temperatures. II) Number projected Hartree-Fock-Bogoliubov (HFB) theory gives us a microscopic understanding of the Interacting Boson Model for nuclei far from closed shells. III) mean field approximations for nuclear bosonic degrees of freedom are discussed in the context of α-condensation in heavy nuclei. (orig.)