Weak error analysis for a nonlinear SPDE approximation of the Dean–Kawasaki equation

Abstract We consider a nonlinear SPDE approximation of the Dean–Kawasaki equation for independent particles. Our approximation satisfies the physical constraints of the particle system, i. e. its solution is a probability measure for all times (preservation of positivity and mass conservation). Using a duality argument, we prove that the weak error between particle system and nonlinear SPDE is of the order N^-1-1/ (d/2+1) N N - 1 - 1 / (d / 2 + 1) log N. Along the way we show well-posedness, a comparison principle, and an entropy estimate for a class of nonlinear regularized Dean–Kawasaki equations with Itô noise.