Spectral densities for response functions of a marginal Fermi liquid model

The O(3) symmetric Anderson model has a Fermi liquid or marginal Fermi liqu id low-energy fixed point, dependent on the parameter V-0, the hybridizatio n matrix element to a local Majorana fermion mode. We use the numerical ren ormalization group method to calculate the spectral densities. For V-0 = 0 (non-Fermi-liquid case) there is a zero mode in the one-particle spectrum w ith a weight which decreases exponentially with U for large U. The scatteri ng with this zero mode induces a \omega\ low energy behavior in the single- particle response functions and a In lot divergence in the dynamic spin sus ceptibility. (C) 1999 Elsevier Science B.V. All rights reserved.