Renormalization-group approach to spectral properties of the two-channel Anderson impurity model

The impurity Green function and dynamical susceptibilities for the two-channel Anderson impurity model are calculated. An exact expression for the self-energy of the impurity Green function as ratio of two correlation functions is given. The imaginary part of the self-energy scales as root vertical bar omega/T-K vertical bar for T -> 0, serving as a hallmark for non-Fermi behavior. The many-body resonance is pinned to a universal value of 1/(2 pi Delta) at omega=0 for arbitrary local occupation in contrary to the single-channel Anderson impurity model. Its shape becomes increasingly more symmetric for the Kondo regimes of the model. The dynamical spin and channel susceptibilities are governed by two energy scales T-K and T-h, and their chi ''(omega) approach a constant value for omega -> 0.