QUASI-PARTICLES AND GAUGE INVARIANCE IN THE THEORY OF SUPERCONDUCTIVITY

Journal Article · Mon Feb 01 00:00:00 EST 1960 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.117.648· OSTI ID:4171413

Nambu, Y

Ideas and techniques known in quantum electrodynamics have been applied to the Bardeen-Cooper-Schrieffer theoryof superconductivity. In an approximation which corresponds to a generalization of the Hartree-Fock fields, one can write down an integral equation defining the selfenergy of an electron in an electron gas with phonon and Coulomb interaction. The form of the equation implies the existence of a particular solution which does not follow from perturbation theory and which leads to the energy gap equation and the quasi-particle picture analogous to Bogoliubov's. The gauge invariance to the first order in the external electromagnetic field, can be maintained in the quasi-particle picture by taking into account a certain class of corrections to the charge-current operator due to the phonon and Coulomb interaction. In fact, generalized forms of the Ward identity are obtained between certain vertex parts and the self- energy. The Miessner effect calculation is thus rendered strictly gauge invariant, but essentially keeping the BCS result unaltered for transverse fields. It is shown also that the integral equation for vertex parts allows homogeneous solutions which describe collective excitations of quasi-particle pairs, and the nature and effects of such collective states are discussed. (auth)

• Research Organization: Univ. of Chicago
• NSA Number: NSA-14-012321
• OSTI ID: 4171413
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 117; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BCS THEORY
DIFFERENTIAL EQUATIONS
ELECTRIC POTENTIAL
ELECTROMAGNETIC FIELDS
ELECTRONS
ENERGY
ENERGY LEVELS
EXCITATION
FIELD THEORY
GASES
GAUGE INVARIANCE
HARTREE-FOCK METHOD
INTEGRAL EQUATIONS
INTEGRALS
INTERACTIONS
MAGNETISM
MATHEMATICS
MEISSNER EFFECT
PARTICLE MODELS
PHONONS
PHYSICS
QUANTUM MECHANICS
QUASI PARTICLES
SELF-ENERGY
SUPERCONDUCTIVITY
VERTEX FUNCTIONS
WARD IDENTITY