The Coherence Field in the Field Perturbation Theory of Superconductivity

TL;DR

This paper revisits the perturbation theory of superconductivity, introducing the concept of a coherence field alongside the Nambu field, which impacts the understanding of pairing interactions and may influence high-temperature superconductor models.

Contribution

It identifies a new coherence field in the perturbation theory of superconductivity, expanding the framework beyond the traditional Nambu field and suggesting potential implications for high-temperature superconductivity.

Findings

The coherence field involves two interaction vertices based on Pauli matrices.

The Hartree integral for off-diagonal self-energy can be finite and large.

Implications for conventional and high-temperature superconductivity are discussed.

Abstract

We re-examine the Nambu-Gorkov perturbation theory of superconductivity on the basis of the Bogoliubov-Valatin quasi-particles. We show that two different fields (and two additional analogous fields) may be constructed, and that the Nambu field is only one of them. For the other field- the coherence field- the interaction is given by means of two interaction vertices that are based on the Pauli matrices tau1 and tau3. Consequently, the Hartree integral for the off-diagonal pairing self-energy may be finite, and in some cases large. We interpret the results in terms of conventional superconductivity, and also discuss briefly possible implications to HTSC.