Frustration, scaling, and local gauge invariance

A variety of two- and three-dimensional random frustrated systems with continuous and discrete symmetries are studied within the Migdal-Kadanoff renormalization-group scheme. The continuous-symmetry XY models are approximated by discretized clock models with a large number of clock states. In agreement with earlier studies of the random gauge XY model using a T=0 scaling approach, a nonzero transition temperature is observed in three-dimensional XY models with O(2) local gauge invariance. Our analysis points to the possible importance of local gauge invariance in determining the lower critical dimensionality of frustrated systems.