Numerical estimation of the $\beta$-function in 2D systems with   spin-orbit coupling
  We report a numerical study of Anderson localization in a 2D system of non-interacting electrons with spin-orbit coupling. We analyze the scaling of the renormalized localization length for the 2D SU(2) model and estimate its $\beta$-function over the full range from the localized to the metallic limits. 
Yoichi Asada, Keith Slevin and Tomi Ohtsuki