On Effective Electron Mass of Silicon MOSFET at Low Electron Density
  The trial wave function method developed in Ref.s \cite{gutz,brink} for the case of narrow {\it s}-band in a perfect crystal is adapted for calculation of the density dependence of the effective mass and the Lande factor in a dilute two-dimensional electron system. We find that the effective mass has a tendency to diverge at a certain critical concentration, whereas the $g$ factor remains finite. 
V.T. Dolgopolov (Institute of Solid State Physics RAS, Russia)