Quantitative convergence in relative entropy for a moderately interacting particle system on ${\mathbb{R}}^d$

Abstract

This article shows how to combine the relative entropy method by D. Bresch, P.-E. Jabin, and Z. Wang in arXiv:1706.09564, arXiv:1906.04093 and the regularized $L^2({\mathbb{R}}^d)$-estimate by Oelschläger (Probability theory and related fields, 1987) to prove a strong propagation of chaos result for the viscous porous medium equation from a moderately interacting particle system in $L^{\infty }(0,T;L^1({\mathbb{R}}^d))$-norm. In the moderate interacting setting, the interacting potential is a smoothed Dirac Delta distribution, however, current results regarding the relative entropy methods for singular potentials do not apply. The result holds on ${\mathbb{R}}^d$ for any dimension $d\ge 1$ and provides a quantitative result where the rate of convergence depends on the moderate scaling parameter and the dimension $d\ge 1$. Additionally, the presented method can be adapted for moderately interacting systems for which a certain convergence probability holds -- thus a propagation of chaos result in relative entropy can be obtained for kernels approximating Coulomb potentials.

arXiv comment20 pages