Effective mass enhancement in two-dimensional electron systems: the role   of interaction and disorder effects
  Recent experiments on two-dimensional (2D) electron systems have found a sharp increase in the effective mass of electrons with decreasing electron density. In an effort to understand this behavior we employ the many-body theory to calculate the quasiparticle effective mass in 2D electron systems. Because the low density regime is explored in the experiments we use the $GW\Gamma$ approximation where the vertex correction $\Gamma$ describes the correlation effects to calculate the self-energy from which the effective mass is obtained. We find that the quasiparticle effective mass shows a sharp increase with decreasing electron density. Disorder effects due to charged impurity scattering plays a crucial role in density dependence of effective mass. 
R. Asgari, B. Davoudi and B. Tanatar