We study the Kondo lattice model with an additional Einstein phonon mode coupled via a Holstein term to the electrons within the dynamical mean-field theory at T = 0. As impurity solver we use the numerical renormalization group. We present results for the paramagnetic case showing the anticipated heavy Fermion physics, including direct evidence for the appearance of a large Fermi surface for antiferromagnetic exchange interaction.
By introducing a Nambu notation, we find that increasing electron-phonon coupling favors superconductivity, which however is not BCS like but shows additional structures in the density of states and the gap function.