We proposed two different methods for simulating theta-vacuum systems. Both can be affected by systematic effects but these errors can be controlled by comparing the results of the two unrelated methods. This has been done for some analytically soluble models and here the same procedure is successfully applied to the interesting case of CP^9 in the scaling region.
@article{arxiv.hep-lat/0309089,
title = {New advances in numerical simulations of theta-vacuum systems},
author = {V. Azcoiti and G. Di Carlo and A. Galante and V. Laliena},
journal= {arXiv preprint arXiv:hep-lat/0309089},
year = {2009}
}