Impurities in graphene and their influence on the Casimir interaction

We study the influence of impurities in graphene described by a scattering rate $\Gamma$ on the Casimir interaction between graphene and an ideal conductor or between two identical sheets of graphene at zero temperature and chemical potential. To this end, we compute the polarization tensor of quasiparticles in graphene and corresponding conductivities for TE and TM channels. The Casimir energy density is evaluated with the help of the Lifshitz formula. We find that depending on the value of mass gap parameter the presence of $\Gamma$ may lead to a slight damping or to a considerable enhancement of the Casimir interaction.