SUPERCONDUCTIVITY - GAUGE FIELD-THEORY FORMULATION

The nonrelativistic BCS theory of superconductivity is studied in the framework which allows an application of field-theoretic methods. The gauge technique of relativistic quantum electrodynamics is shown to be a suitable basis which makes it feasible to extend BCS theory beyond the original weak coupling approximation. We derive a relation between the superconducting transition temperature, the Debye temperature, the effective coupling constant and the effective electron mass. In addition to the BCS type solution, we establish an interesting new solution which corresponds to a high transition temperature.