A cluster algorithm for the Z2 Kalb-Ramond model

A cluster algorithm is presented for the Z2 Kalb-Ramond plaquette model in four dimensions which dramatically reduces critical slowing. The critical exponent z is reduced from z > 2 (standard Metropolis algorithm) to z = 0.32 ± 0.06. The cluster algorithm updates the monopole known to be responsible for the second order phase transition.