Scaling topological charge in the CP3 model using a fixed point action

Abstract We define a fixed point action in two-dimensional lattice CP N −1 models. The fixed point action is a classical perfect lattice action, which is expected to show strongly reduced cut-off effects in numerical simulations. Furthermore, the action has scale invariant instanton solutions, which enables us to define a topological charge without topological defects. We present results for the scaling of the topological suceptibility from a Monte Carlo simulation in the CP 3 model.