Variational principle in stochastic quantization and 1/N expansion

In stochastic quantization of O(N) scalar field theories, the variational scheme of Amundsen and Damgaard is analysed in the framework of a 1/N expansion. In the large-N limit the usual saddle point result is retrieved. Successive corrections in 1/N to the trial field are obtained analytically in a simple iterative process, with improved minimization at each step. A solvable toy model is treated explicitly showing very rapid convergence even for N = 3. For the O(N) φ4 theory a minimization order by order in 1/N is shown to be the only feasible one in practice. (author) 11 refs., 2 figs