Fermi liquid corrections for non-equilibrium transport through an SU(N) Anderson impurity with arbitrary electron fillings

We extend a Fermi-liquid description, which has recently been revisited to derive exact nonequilibrium transport formulas applicable to the particle-hole asymmetric case [1,2], for studying the Anderson impurity model with N orbitals at low temperatures T and at low bias voltages eV. We also apply the formulas to the SU(N) symmetric case and calculate order T² and (eV)² contributions of the differential conductance dI/dV, by using the numerical renormalization group (NRG) approach and also the 1/(N-1) expansion [3]. Our results, obtained in a wide range of electron fillings, show that contributions of three-body fluctuations that enter through nonlinear susceptibilities play an important role as a gate voltage varies away from the particle-hole symmetric point where the impurity levels are half-filled. Furthermore, the contributions of three body fluctuations show an oscillatory behavior as gate voltage ε_d varies and, the three body fluctuations decrease as the number of the orbital N increases.
[1] M. Filippone, C. P. Moca, A. Weichselbaum, J. von Delft, and C. Mora, Phys. Rev. B 98, 075404 (2018).
[2] A. Oguri and A. C. Hewson, Phys. Rev. Lett. 120, 126802 (2018)
[3] A. Oguri, Phys. Rev. B 85, 155404 (2012)