Large N Limit on Langevin Equation: Two-Dimensional Nonlinear Sigma   Model
  We study the stochastic quantization of two-dimensional nonlinear sigma model in the large $N$ limit. Our main tool is the {\it effective} Langevin equation with which we investigate nonperturbative phenomena and derive the results which are same as the path integral approach gives. 
R. Mochizuki and K. Yoshida