θ dependence of the CP9 model -: art. no. 056006

We apply to the CP9 model two recently proposed numerical techniques for the simulation of systems with a theta term. The algorithms, successfully tested in the strong coupling limit, are applied to the weak coupling region. The results agree and errors have been evaluated and are at the % level. The results scale well with the renormalization group equation and show that, for CP9 in the presence of a theta term, CP symmetry is spontaneously broken at theta=pi in the continuum limit.