Phenomenological plasmon broadening and relation to the dispersion
  Pragmatic ways of including lifetime broadening of collective modes in the electron liquid are critically compared. Special focus lies on the impact of the damping parameter onto the dispersion. It is quantitatively exemplified for the two-dimensional case, for both, the charge (`sheet'-)plasmon and the spin-density plasmon. The predicted deviations fall within the resolution limits of advanced techniques. 
Raphael Hobbiger, J\"urgen T. Drachta, Dominik Kreil, Helga M. B\"ohm
cond-mat.mes-hall