Investigation of the pion condensation threshold in finite nuclei

The threshold condition for pionic instabilities in finite nuclei is investigated by evaluating the response function for pion-like nuclear excitations (i.e. isovectorJ ^π =0^?, 1⁺, 2^?, ... excitations). The onset of pion condensation is then defined as the point where the response function for givenJ ^π becomes infinite at frequencyω=0. Using a momentum space representation for the response function which allows to establish clear connections to the nuclear matter case, we find that for angular momentaJ smaller than a maximum value which depends on the size of the nucleus, the threshold condition is almost the same as for infinite matter. We also study the systematics of this phenomenon as a function of nuclear mass number.