The density and entropy of the pion excitations in the nuclear matter

The thermodynamical properties of the pion excitations in the isotopically symmetric nuclear matter are investigated. The expressions for the density and the entropy of the pion excitations are obtained, that are then transformed for the state of the system near by the pion field instability. The calculations have been fulfiled on the basis of the application of the quantum field theory methods in the many-body problem for nonzero temperature by means of the temperature Green functions. The obtained results give the dependence of the density and the entropy of the pion excitations on the temperature and density of the nuclear matter