Fixed Point Action and Topology in the CP^3 Model

Abstract

We define a fixed point action in two-dimensional lattice ${\rm CP}^{N-1}$ models. The fixed point action is a classical perfect lattice action, which is expected to show strongly reduced cutoff effects in numerical simulations. Furthermore, the action has scale-invariant instanton solutions, which enables us to define a correct topological charge without topological defects. Using a parametrization of the fixed point action for the ${\rm CP}^{3}$ model in a Monte Carlo simulation, we study the topological susceptibility.Comment: 27 pages, 5 figures, typeset using REVTEX, Sec. 6 rewritten (additional numerical results), to be published in Phys.Rev.