Abstract
Using a recently developed perturbative renormalization group (RG) scheme, we calculate analytically the spectral function of a Kondo impurity for either large frequencies or large magnetic field B and arbitrary frequencies. For large the spectral function decays as with prefactors which depend on the magnetization. The spin-resolved spectral function displays a pronounced peak at with a characteristic asymmetry. In a detailed comparison with results from numerical renormalization group (NRG) and bare perturbation theory in next-to-leading logarithmic order, we show that our perturbative RG scheme is controlled by the small parameter Furthermore, we assess the ability of the NRG to resolve structures at finite frequencies.
- Received 8 January 2003
DOI:https://doi.org/10.1103/PhysRevB.68.014430
©2003 American Physical Society