Low-energy properties of an out of equilibrium Anderson model Original Research Article

The Anderson impurity model is studied under a finite bias voltage V applying a microscopic theory of the local Fermi-liquid by Yamada and Yosida to the Keldysh diagrammatic formalism. Using the Ward identities for the nonequilibrium Greenʹs functions, the low-energy behavior of the self-energy has been deduced exactly up to terms of order ω2, T2 and V2. The coefficients are defined with respect to the equilibrium ground state, and contain all contributions of the Coulomb interaction U. In this report, we examine the U dependence of the spectral function and differential conductance in the vicinity of the equilibrium by computing the coefficients explicitly with the Bethe ansatz solution in the electron–hole symmetric case.