Dynamic renormalization-group theory of interfaces: Model A

The dynamics of the interface of an Ising-like system driven by relaxational dynamics is studied within the framework of a first-order ε expansion near four dimensions. The starting point uses the static and dynamic equations of the bulk system (model A) and an interface is produced by imposing suitable boundary conditions. The interfacial dispersion relation is of the form ${\omega }_q$=-iΓ$q^z$Ω(qξ), with z=2+O(${\epsilon }^2$) and Ω(x) universal, and satisfies the Goldstone theorem for the spontaneously broken Euclidean symmetry.