Dynamic Hubbard Model: Effect of Finite Boson Frequency

TL;DR

This paper investigates how finite boson frequency influences superconductivity in the Dynamic Hubbard Model, revealing that finite frequency enhances the superconducting tendency through a generalized transformation and high frequency expansion.

Contribution

It introduces a method to analyze finite boson frequency effects in the Dynamic Hubbard Model, extending previous infinite frequency results.

Findings

Finite boson frequency enhances superconductivity.

Generalized Lang-Firsov transformation effectively captures finite frequency effects.

High frequency expansion provides analytical insights into the model.

Abstract

Dynamic Hubbard models describe coupling of a boson degree of freedom to the on-site electronic double occupancy. In the limit of infinite boson frequency this coupling gives rise to a correlated hopping term in the effective Hamiltonian and to superconductivity when the Fermi level is near the top of the band. Here we study the effect of finite boson frequency through a generalized Lang-Firsov transformation and a high frequency expansion. It is found that finite frequency enhances the tendency to superconductivity in this model.