Scaling topological charge in the CP^3 spin model

The CP^3 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 around unity. We compare our results with recent multigrid data on the massgap 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 chi_t / m^2 = 0.156(2) in the continuum limit.Comment: 11 pages, 3 ps-figure

High Precision Simulation Techniques for Lattice Field Theory

An overview is given over the recently developed and now widely used Monte Carlo algorithms with reduced or eliminated critical slowing down. The basic techniques are overrelaxation, cluster algorithms and multigrid methods. With these tools one is able to probe much closer than before the universal continuum behavior of field theories on the lattice.Comment: (Talk given at the 4th International Conference on Computational Physics PC92, Prague, August 1992), 11 pages, 1 ps figur

Triviality of φ4\varphi^4 theory in a finite volume scheme adapted to the broken phase

We study the standard one-component $\varphi^4$-theory in four dimensions. A renormalized coupling is defined in a finite size renormalization scheme which becomes the standard scheme of the broken phase for large volumes. Numerical simulations are reported using the worm algorithm in the limit of infinite bare coupling. The cutoff dependence of the renormalized coupling closely follows the perturbative Callan Symanzik equation and the triviality scenario is hence further supported.Comment: 10 pages, 2 figure