Quasiparticle lifetime in a bilayer system

In a bilayer system, the decay rate of an excited quasiparticle is enhanced by momentum and energy transfer to low energy plasmonic modes. These correspond to antisymmetric charge density oscillations that propagate acoustically, with ω∼q. Within the random phase approximation, we study the relaxation rate dependence on the excitation energy above the Fermi level and suggest an experimental situation that can probe this estimate.