Exact single spin flip for the Hubbard model in d=infinity

It is shown that the dynamics of a single down arrow-electron interacting with a band of up arrow-electrons can be calculated exactly in the limit of infinite dimension. The corresponding Green function is determined as a continued fraction. It is used to investigate the stability of saturated ferromagnetism and the nature of the ground state for two generic nonbipartite infinite dimensional lattices. Non-Fermi-liquid behavior is found. For certain dopings the down arrow-electron is bound to the up arrow-holes.