Confined gap excitation and multielectron localization in magnetic alloys

The degenerate Anderson model with a nonlinear electron dispersion and an energy dependent hybridization is proven to exhibit hidden integrability and is diagonalized by the Bethe ansatz. If the impurity $f$-level energy lies below the conduction band edge, the spectrum of the system is shown to contain pairs of confined ``gap excitations'' and their heavy bound complexes. In addition, multielectron localized states due to a pinning of gap bound complexes to the impurity are predicted.