RELATIVISTIC PARTICLE-HOLE AND DELTA-HOLE EXCITATIONS FOR PION PROPAGATOR IN NUCLEAR-MATTER

The relativistic particle-hole and delta-hole polarization insertions for pion propagator are calculated by using particle-hole-antiparticle representation of nucleon and delta propagators in nuclear matter. Th e short-range correlations between nucleon-nucleon, nucleon-delta and delta-delta are included via Landau-Migdal parameter g' in the random phase approximation. We calculate the dispersion relations for pions a nd find out that the damped pion condensation is removed by the short- range correlation and there is a long gap in the dispersion relation.