  The problem of velocity selection of reaction-diffusion fronts has been
widely investigated. While the mean field limit results are well known
theoretically, there is a lack of analytic progress in those cases in which
fluctuations are to be taken into account. Here, we construct an analytic
theory connecting the first principles of the reaction-diffusion process to an
effective equation of motion via field-theoretic arguments, and we arrive at
the results already confirmed by numerical simulations.
