The d-dimensional sine-Gordon model in the presence of random fields

We study the properties of a d-dimensional sine-Gordon model in the presence of a random field that couples linearly to the sine-Gordon field using the Wilson renormalization group approach via the replica trick. No stable fixed point is found for dimensionalities d<4, corresponding to the absence of long-range order. Such a situation seems to occur in experiments on impurity-pinned charge-density-wave systems in which a “glassy behaviour” appears to be induced by arbitrarily weak symmetry-breaking randomness.