1/(N-1) expansion approach to full counting statistics for the SU(N) Anderson model

TL;DR

This paper introduces a novel 1/(N-1) expansion method for analyzing full counting statistics in the SU(N) Anderson model, providing accurate results for current fluctuations in quantum dots.

Contribution

The paper develops a new perturbative approach based on 1/(N-1) expansion, differing from traditional large N theories, and validates it against numerical renormalization group results.

Findings

Close agreement with NRG at N=4

Applicable for N>4

Accurate cumulant calculations for nonequilibrium current

Abstract

We apply a recently developed 1/(N-1) expansion to the full counting statistics for the N-fold degenerate Anderson impurity model in the Kondo regime. This approach is based on the perturbation theory in the Coulomb interaction U and is different from the conventional large N theories, such as the usual 1/N expansion and non-crossing approximation. We have confirmed that the calculations carried out up to order 1/(N-1)^2 agree closely with those of the numerical renormalization group at N=4, where the degeneracy is still not so large. This ensures the applicability of our approach for N>4. We present the results of the cumulants of the probability distribution function for a nonequilibrium current through a quantum dot in the particle-hole symmetric case.