Why $$ -\Delta_g u+\lambda=\lambda \frac{e^{2 u}}{\int_M e^{2 u} d \mu_g} $$type PDE is called 'mean-field equation'? It's closely related to moser-trudinger inequality, there are many classical papers on it google scholar.
What I want to ask is that why this equation is called 'mean-field equation'? Its backgrounds are almost all about conformal geometry (prescribed curvature problem) and physics, but it seems that these backgrounds have nothing to do with the description of 'mean-field theory' I searched on google mean-field theory.
If you know about its history, I will be very glad.