Pion condensation

Because of the lack of an underlying gauge field theory, pion condensation must be investigated phenomenologically. The pionic spectrum of nucleon matter is studied. A difference between three possible pion condensates is noticed: a neutral pion condensate is a standing wave with a chemical potential zero, a charged pion condensate is a travelling wave. By replacing pion field operators with their expectation values all virtual pion effects such as N-N interactions are eliminated. N-N interactions must therefore be ''put in by hand.'' The equation of state is close to that for neutron matter below p /SUB o/ . Neutron stars are discussed. Finally, for heavy ion collisions, normal nuclear ground states with and without pion condensates are considered. The possibility that high density matter created in heavy ion collision may also contain condensates is touched upon