Cyclotron resonance line shape function from the equilibrium density projection operator technique.

In this work, we present the calculation processes for obtaining the scattering factor for an electron-phonon system using the equilibrium density projection operator technique. We introduce two useful identities necessary to expand the scattering factor. We derive a cancellation relation which simplifies the expansion of the scattering factor. We obtain the cyclotron resonance line shape function in the case of weak interaction. Finally, we compare our results with other theories.