Treatment of opposite-parity states in the Jolos approach

The low-energy physical properties of odd-mass nuclei are explained in a theoretical approach based on the approximation that the quadrupole vibrations and the pairing forces could be singled out as in the pairing-plus-quadrupole models. To reproduce the anharmonicity effects the core states basis is enlarged including two- and more-phonon states. This is achieved using the approach presented by Jolos based on the derivation of a system of linear equations for the energy levels and the corresponding wave function components. The system obtained is modified in a way allowing to treat also the opposite-parity states of the odd nucleus. This is done taking into account the Pauli principle obeyed by the fermion operators which are part of the composite boson quadupole operator. The deviation of the presented approach from the self-consistent theory (developed by Klein at al.) is briefly discussed. 1 fig., 15 refs