Polaronic Quasiparticles in a Strongly Correlated Electron Band
  We show that a strongly renormalized band of polaronic quasiparticle excitations is induced at the Fermi level of an interacting many-electron system on increasing the coupling of the electrons to local phonons. We give results for the local density of states at zero temperature both for the electrons and phonons. The polaronic quasiparticles satisfy Luttinger's theorem for all regimes considered, and their dispersion shows a kink similar to that observed experimentally in copper oxides. We calculate the quasiparticle weight factor $z$ and deduce the local effective inter-quasiparticle interaction $\tilde U$. Our calculations are based on the dynamical mean field theory and the numerical renormalization group for the hole-doped Holstein-Hubbard model and large on-site repulsion. 
W. Koller, A.C. Hewson and D.M. Edwards