Abstract
In many-body problem various methods of quantum field theory have been frequently used and have led to successful results. The purpose of this lecture is to show how, by using ideas from quantum field theory, it is possible to formulate the theory of superconductivity from a different point of view which offers some advantages over the usual formulation. By applying the “self consistent quantum field theory”(1) we have been developing for some years a formulation of superconductivity which has been called boson formulation of superconductivity.(2) In the course of this application we have introduced the concept of boson transformations (3,4) which are invariant transformations in the sense that they leave invariant the equations of motion but may modify the ground-state expectation values of some of the observables. The use of these invariant transformations has turned out to be a very powerful tool in the study of all those situations related to the presence of a non-homogeneous structure of the ground state. The introduction of the concept of boson transformations in the framework of the self-consistent method provides a technique of computation which has been called “the boson method”.(2) Application of this method to the study of superconductivity enables us to describe in a systematic and unified way many different phenomena; besides, the study of these phenomena is made much more simple.
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Mancini, F. (1974). Use of Invariant Transformations in Problems of Superconductivity. In: Caianiello, E.R. (eds) Renormalization and Invariance in Quantum Field Theory. NATO Advanced Study Institutes Series, vol 5. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-8909-9_8
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