Comment on "Current fluctuations in non-equilibrium diffusive systems:   an additivity principle"
  We point out that the "additivity principle" and "scaling hypothesis" postulated by Bodineau and Derrida in Phys. Rev. Lett 92, 180601 (2004), follow naturally from the saddle point evaluation of a diffusive field theory. 
Eugene V. Sukhorukov, and Andrew N. Jordan