Pion spectra in nuclear matter at high density and high temperature

Expressions determining the polarization operator R(w, k, T) are obtained for pions in nuclear matter consisting of interacting nucleons, D/sub 33/ isobars, and pions at a high density p and temperature T. The presence of interacting pions in the hot nuclear matter is included; the pions are in equilibrium with the nuclear matter. The singularities of the pion temperature Green's function D(w, k, T) are studied for different T. These singularities determine the pion spectrum. The dependence of the critical density p/sub cr/(T) on T is obtained, and the conditions of appearance of pion condensate instabilities at high density p and temperature T are studied. Such conditions arise during collisions of heavy nuclei.