Scaling topological charge in the CP3 spin model

The CP3 spin model is simulated at large correlation lengths in two dimensions. An overrelaxation algorithm is employed which yields reduced critical slowing down with dynamical exponents z≅1. We compare our results with recent multigrid data on the mass gap m and the spin susceptibility and confirm the absence of asymptotic scaling. As a new result we find scaling for the universal topological susceptibility with values extrapolating to χt/m2=0.156(2) in the continuum limit. (orig.)