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Collective Quantum Fields
Author(s) -
Kleinert H.
Publication year - 1978
Publication title -
fortschritte der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.469
H-Index - 71
eISSN - 1521-3978
pISSN - 0015-8208
DOI - 10.1002/prop.19780261102
Subject(s) - resummation , feynman diagram , path integral formulation , physics , perturbation theory (quantum mechanics) , quantum , quantum field theory , pairing , quantum mechanics , fermi gamma ray space telescope , series (stratigraphy) , theoretical physics , mathematical physics , superconductivity , quantum chromodynamics , paleontology , biology
A general quantum field theory of collective excitations is presented for many‐body systems. Lagrangians involving fundamental particles are transformed to collective fields exactly via Feynman path integrals. Graphically, this amounts to a complete resummation of the perturbation series without the danger of double counting. Plasma and pairing effects provide special examples corresponding to mutually complementary transformations. Bose and Fermi systems can be treated on equal footing. The methods are illustrated by giving the exact collective Lagrangian for the BCS model and approximate ones for type II superconductors and 3 He.