SINGULAR LOW-ENERGY PROPERTIES OF AN IMPURITY MODEL WITH FINITE-RANGEINTERACTIONS

A resonant-level impurity Hamiltonian with finite range interactions i s considered. It is shown that for repulsive interactions above a crit ical threshold, the model displays scale invariant properties unlike t hose of a Fermi liquid. The various correlation functions behave as po wer laws with nonuniversal exponents depending on the interactions. At the transition between the Fermi-liquid and non-Fermi-liquid regimes the resistivity behaves as A+B/ln(T)2, whereas it behaves as A+BT(nu) with nu > 0 in the latter.