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Auxiliary fields and linear response in Lagrangian many body theory

1971; IOP Publishing; Volume: 4; Issue: 4 Linguagem: Inglês

10.1088/0022-3719/4/4/002

1747-3802

David C. Sherrington,

Physics of Superconductivity and Magnetism

A brief discussion is presented of the use of auxiliary field techniques in a functional integral formulation of many body theory. By using a Lagrangian representation for the Green functions from the outset a description is obtained in which true and auxiliary fields are treated on a more nearly equal basis than in partition function methods. The interacting fields are shown to have physical significance, their propagators leading to linear response functions of the true system. A diagrammatic representation analogous to that of a true interacting field problem is shown to follow in a straightforward manner. Transformations among fields are considered.