Special Session 9: Stochastics and randomness in physical models

Small Noise Asymptotics for Nonlinear Reaction-Diffusion Equations
giuseppina guatteri
Politecnico di Milano
Italy
Co-Author(s):    Sandra Cerrai, Gianmario Tessitore
Abstract:
This talk is based on joint work with Sandra Cerrai and Gianmario Tessitore. We present well-posedness and small-noise asymptotic results for a class of stochastic reaction-diffusion equations on bounded domains, driven by nonlinear and temporally nonlocal multiplicative noise. The diffusion coefficient depends on the solution through a conditional expectation at the final time, while the reaction term is only assumed to be continuous and quasi-dissipative, with no growth bounds or local Lipschitz assumptions. To handle these difficulties, we avoid relying on the theory of infinite-dimensional quasilinear PDEs and instead work directly at the SPDE level, combining a mild formulation with a Salins-type solution map and contraction arguments. This yields existence and uniqueness for sufficiently small noise, as well as a large deviation principle for the laws of the solution trajectories.