QUASI-PARTICLE DISPERSION OF THE 2D HUBBARD-MODEL - FROM AN INSULATORTO A METAL

On the basis of quantum Monte Carlo results the evolution of the spect ral weight A(k, omega) of the two-dimensional Hubbard model is studied from insulating to metallic behavior. As observed in recent photoemis sion experiments for cuprates, the electronic excitations display esse ntially doping-independent features; a quasiparticlelike dispersive na rrow band of width of the order of the exchange interaction J and a br oad valence- and conduction-band background. The continuous evolution is traced back to one and the same many-body origin: the doping-depend ent antiferromagnetic spin-spin correlation.