Single Particle Excitation From Correlated Materials:
The Phenomenological Approach

Konrad Matho

Centre de Recherches sur les Tres Basses Temperatures, Grenoble, France

In the interpretation of ARPES near the Fermi edge, an effective one-band model and scalar selfenergy function is often assumed. We point out that interference effects are expected in multi-orbital systems, even close to the Fermi edge. These become apparent at increased angular resolution and can be influenced by changing the frequency and polarisation of the incoming light beam. We review our phenomenological approach to the multiorbital selfenergy, needed to describe these effects within the sudden approximation.