Spherical surface growth models

We study several surface growth models obtained by treating and replacing the non-linear term in the noisy Burgers equation or the KPZ equation by a mean spherical condition. We want to explore the consequences of such constraints on the Edwards-Wilkinson (EW) interface. In those exactly solvable models, one has to solve the spherical conditions and then we can derive the two-time quantities (the correlation function and the response function). Therefore, we have access to the non-equilibrium exponents and compare them to those of the EW model or the KPZ model.