Duality in the Kondo model and perturbative approach to strong coupling theory

TL;DR

This paper explores the duality in the Kondo model, linking weak and strong coupling regimes, and demonstrates that perturbation theory aligns qualitatively with numerical results near the Kondo temperature.

Contribution

It introduces a duality framework in the Kondo model and applies perturbation theory to analyze strong coupling behavior, providing insights into conductance limits.

Findings

Unitary conductance limit at zero temperature

Qualitative agreement of perturbation theory with NRG and Bethe ansatz near T_K

Identification of the strong coupling model as 1/J dual to the original

Abstract

We investigate the duality in the Kondo model. Starting from the s-d model with the coupling constant $J$, the strong coupling model with the constant of 1/J is identified. The model shows the unitary limit of the conductance, $G=2 e^{2}/h$ at zero temperature. The perturbation theory of the model gives qualitative agreement with the results of numerical renormalization group and Bethe ansatz near $T=T_{K}$.