Pionic properties of finite nuclei

Dynamics of nuclei which is induced by pions exchanged between nucleons is studied in view of pion condensation. Formulating a wave equation for pions propagating in a nuclear system, we investigate pionic eigenmodes of the nucleus. The threshold for pion condensation severely depends on the nuclear correlation parameter g'. We obtain the critical correlation parameter g'sub(c) = 0.58 for pion condensation in 16O, while the physical value of g' in the nucleus is estimated to be in the region 0.8 >= g' >= 0.5. In the case g' < g'sub(c), the shell model state is unstable for some pionic eigenmodes and pions are condensed. In the coherent state approximation, we express a nuclear Hartree state, in which some symmetries are broken due to the Hartee potential induced by the pion field. A physical nuclear state is obtained by projecting the Hartree state onto an eigenstate of nuclear quantum numbers. Some excited states which are pionic-analogue to the ground state are predicted from the projection. (author)