Real-frequency quantum field theory applied to the single-impurity Anderson model

Understand

A major challenge in the field of correlated electrons is the computation of dynamical correlation functions.

• For comparisons with experiment, one is interested in their real-frequency dependence.
• This is difficult to compute, as imaginary-frequency data from the Matsubara formalism require analytic continuation, a numerically ill-posed problem.
• Here, we apply quantum field theory to the single-impurity Anderson model (AM), using the Keldysh instead of the Matsubara formalism with direct access to the self-energy and dynamical susceptibilities on the real-frequency axis.