Functional-integral approach to Gaussian fluctuations in Eliashberg theory
Functional-integral approach to Gaussian fluctuations in Eliashberg theory
The Eliashberg theory of superconductivity is based on a dynamical electron-phonon interaction as opposed to a static interaction present in BCS theory. The standard derivation of Eliashberg theory is based on an equation of motion approach, which incorporates certain assumptions such as Migdal's approximation for the pairing vertex. In this …