Goldstone, J.; Field Theories with "Superconductor'' Solutions
Nuovo Cim. 19 (1961) 154;
The conclusion for the existence of non-perturbative type "superconductor'' solutions of field theories are examined. A non-covariant canonical transformation method is used to find such solutions for a theory of a fermion interacting with a pseudoscalar boson. A covariant renormalizable method using Feynman integrals is then given. A "superconductor'' solution is found whenever in the normal perturbative-type solution the boson mass squared is negative and the coupling constants satisfy certain
inequalities. The symmetry properties of such solutions are examined with the aid of a simple model of self-interacting boson field. The solutions have lower symmetry than the Lagrangian and contain mass zero bosons.
Related references See also N. N. Bogolyubov, JETP 7 (1958) 51;
N. N. Bogolyubov, Zh. Eksp. Teor. Fiz. 34 (1958) 73;
ex, qn, mass
Prediction of unavoidable massless bosons if global symmetry of the Lagrangian is spontaneously broken.