Single particle excitations of the Kondo lattice

We present a simple theory for the description of the single particle excitations in the Kondo lattice model. Thereby we derive an `effective Hamiltonian' which describes the coherent propagation of single particle-like fluctuations on a strong coupling background. Even for f-electrons which are replaced by Kondo-spins, the resulting spectral function obeys the Luttinger theorem including the f-electrons, and our calculation fully reproduces the nontrivial variation of the spectral function and momentum distribution with electron density and parameter values as seen in exact diagonalization and density matrix renormalization group studies.