Effective field theory for interface delocalization transitions

Semi-infinite systems are considered which give rise to a delocalization transition of the interface between two coexisting phases. Since the interface position becomes a zero mode at the transition, interface fluctuations invalidate mean-field theory for space dimension $d<~3$. An effective field-theoretic model for this zero mode is obtained via the collective-coordinate method. Results for a simplified version of this model in $d=2$ and in $d=3$ are reported.